I'm not sure of a location where this would be written; however I'm not sure its quite that simple. Casters have their "casting stat" under their spells description. For other classes you can simply read the abilities to gain a grasp of what they benefit from. Everything else is about your build preference. Do you want to use a greatsword and stand on the frontlines without worry or care? Then STR and CON may be better for you than INT or CHA.
Spells: A cleric casts divine spells which are drawn from the cleric spell list presented in Spell Lists. Her alignment, however, may restrict her from casting certain spells opposed to her moral or ethical beliefs; see chaotic, evil, good, and lawful spells. A cleric must choose and prepare her spells in advance.
To prepare or cast a spell, a cleric must have a Wisdom score equal to at least 10 + the spell level. The Difficulty Class for a saving throw against a cleric's spell is 10 + the spell level + the cleric's Wisdom modifier.
Like other spellcasters, a cleric can cast only a certain number of spells of each spell level per day. Her base daily spell allotment is given on Table: Cleric. In addition, she receives bonus spells per day if she has a high Wisdom score (see Table: Ability Modifiers and Bonus Spells).
Clerics meditate or pray for their spells. Each cleric must choose a time when she must spend 1 hour each day in quiet contemplation or supplication to regain her daily allotment of spells. A cleric may prepare and cast any spell on the cleric spell list, provided that she can cast spells of that level, but she must choose which spells to prepare during her daily meditation.
Each Spells: description will have similar wording, only with a different stat based on the class.
WNcTry4el, I think you'd benefit from picking a few classes that sound interesting to you reading through the basics on them. As was mentioned already, stats are not as cut and dry in Pathfinder as they may be in some other systems. That said, I'll try to give you a bit of a head starts:
Barbarian: The barbarian is a brutal berserker from beyond the edge of civilized lands.
Most Barbarians gain the greatest benefits from Strength and Dexterity.
Bard: The bard uses skill and spell alike to bolster his allies, confound his enemies, and build upon his fame.
Most Bards gain the greatest benefits from Charisma and Dexterity.
Cleric: A devout follower of a deity, the cleric can heal wounds, raise the dead, and call down the wrath of the gods.
Most Clerics gain the greatest benefits from Wisdom and Strength.
Druid: The druid is a worshiper of all things natural—a spellcaster, a friend to animals, and a skilled shapechanger.
Most Druids gain the greatest benefits from Wisdom and either Dexterity or Strength.
Fighter: Brave and stalwart, the fighter is a master of all manner of arms and armor.
Most Fighters gain the greatest benefits from Strength and Dexterity.
Monk: A student of martial arts, the monk trains his body to be his greatest weapon and defense.
Most Monks gain the greatest benefits from Strength, Wisdom, and Dexterity.
Paladin: The paladin is the knight in shining armor, a devoted follower of law and good.
Most Paladins gain the greatest benefits from Strength and Charisma.
Ranger: A tracker and hunter, the ranger is a creature of the wild and of tracking down his favored foes.
Most Rangers gain the greatest benefits from Strength and/or Dexterity and Wisdom.
Rogue: The rogue is a thief and a scout, an opportunist capable of delivering brutal strikes against unwary foes.
Most Rogues gain the greatest benefits from Dexterity.
Sorcerer: The spellcasting sorcerer is born with an innate knack for magic and has strange, eldritch powers.
Most Sorcerers gain the greatest benefits from Charisma.
Wizard: The wizard masters magic through constant study that gives him incredible magical power.
Most Wizards gain the greatest benefits from Intelligence.
Alchemist: The alchemist is the master of alchemy, using extracts to grant him great power, mutagens to enhance his form, and bombs to destroy his enemies.
Most Alchemists gain the greatest benefits from Intelligence and Strength or Dexterity.
Cavalier: Mounted upon his mighty steed, the cavalier is a brave warrior, using his wit, charm, and strength at arms to rally his companions and achieve his goals.
Most Cavaliers gain the greatest benefits from Strength.
Inquisitor: Scourge of the unfaithful and hunter of horrors, the inquisitor roots out the enemies of her faith with grim conviction and an array of divine blessings.
Most Inquisitors gain the greatest benefits from Wisdom and Strength or Dexterity.
Oracle: Drawing upon divine mysteries, the oracle channels divine power through her body and soul, but at a terrible price.
Most Oracles gain the greatest benefits from Charisma.
Summoner: Bonded to a mysterious creature called an eidolon, the summoner focuses his power on strengthing that connection and enhancing his strange, otherworldy companion.
Most Summoners gain the greatest benefits from Charisma.
Witch: Lurking on the fringe of civilization, the witch makes a powerful connection with a patron that grants her strange and mysterious powers through a special familiar.
Most Witches gain the greatest benefits from Intelligence.
Magus: Magi spend much of their time traveling the world, learning whatever martial or arcane secrets they can find. They might spend months learning a new sword-fighting style from a master warrior, while simultaneously moonlighting in the local library, poring through tomes of ancient lore. Most who take this path dabble in all sorts of lore, picking up anything that might aid them in their search for perfection.
Most Magus gain the greatest benefits from Intelligence and either Strength or Dexterity.
Gunslinger: Gunslingers are thunderous artillery, often found where the fighting is fiercest. Brave, clever, and frequently foolhardy, many gunslingers push to position themselves at close range, barrels blazing, to take down their foes and demoralize their enemies. Other gunslingers are masters of distant death, picking off enemies from afar with their strange and wondrous weapons.
Most Gunslingers gain the greatest benefits from Dexterity.
Ninja: The ninja spends almost all of her time honing her skills, practicing her art, or working on her next assignment. Even when not specifically working, the ninja is ever vigilant and ready for the situation to turn deadly. Her line of work earns her many enemies, but it is a list that she frequently reduces through assassination and misdirection. The ninja is an alternate class for the rogue core class.
Most Ninjas gain the greatest benefits from Dexterity and Charisma.
Samurai: While typically sworn to the service of a lord, a samurai is usually given free reign as to how he performs that service. As such, samurai can sometimes be found with other adventurers, taking the fight to the enemies of their masters. Other samurai become ronin, striving to serve an ideal without paying fealty to a lord. In either case, samurai make powerful allies, capable of withstanding nearly any harm while dispatching their foes with deadly precision. The samurai is an alternate class for the cavalier base class.
Most Samurais gain the greatest benefits from Strength.
Class name in bold
Class description (from the PRD) in normal font
My own thoughts/comments in italics.
Also there are a lot of "Guides to <xxxx> Class" out there. Broken Zenith has compiled a fairly complete list of the guides HERE. Pick a class you are interested in and read over the guide and it should give you suggestions on stats, etc.
-- david
Basically everything MechE said I agree with, with the caveat that melee classes in general (and Barbarians especially) benefit from having a high Constitution as well, in some cases more so than a high Dexterity.
On barbarians I would say CoN is more important than anything else, including strength. I mean with rage you can be an effective combatant with a base 14 strength (18 after rage), but a high con is going to be required to keep rage up and stay alive longer due to the AC penalty.
everyone needs con, and the bonus rage rounds for barbarians are rather low in the grand scheme of things. You only get one round extra per day for every 2 con. Getting an 18 con compared to a 14 only means 2 more rage rounds. A barbarians gets more than that from just leveling up. Later on, the difference would only be 24 vs 26.
Do you want the barbarian that has to rage just to have as much strength as the fighter? And the rage rounds only go so far early on, even with a huge con. So why not just be a decent melee character without rage, and let rage be a nice boost?
Anyway, for martial classes on a 20 point buy, I tend to prefer dividing it up into one 16 and two 14's. Apply as needed, and try to get a racial bonus to the highest score. So it might be 18, 14, 14 for a melee character, but 14, 18, 14 for a ranged one. This might work well too for a pure caster if you forget strength and just put the 16(+2) into the casting stat.
For melee casters, I would probably divide it among four 14's, and with a racial bonus to strength or dex. This hold true even if I am thinking of a full caster like a cleric or druid. This is because a casting stat above 14 is only important for maybe one or two extra spells and a higher save DC during the lower levels, and a higher strength or dex (based on weapon style) would be far more noticeable. The need for having your casting stat high enough to cast a spell does not become a problem until mid levels, and by then you would have had at least a couple ability score increases and access to stat boosting equipment. So a 14 is fine for a melee/archer caster.
Of course, this is all based on the idea that I am not dumping stats. You are free to do so, and you could get higher scores or bonuses in more of your important stats.