I'm not super knowledgeable when it comes to playing the half-caster classes, but I do know that a lot of the traditional fighting styles (two weapon fighting, archery) tend to suck up a lot of feat slots and on a half caster using his early feats to do class or ability score related shenanigans, like an Eldritch Scion Magus taking Noble Scion and Desna's Shooting Star, or taking weapon finesse/focus into piercing or slashing grace, or a bard taking flagbearer and lingering performance.
What do people find to the best, or at least most efficient and useful combat feats to be picking up as a half caster?
Obviously this varies greatly by build, but I'm not really sure where I'd want my half casting class to go later on in terms of combat options, or when I don't necessarily need them. For example, If you're a magus and plan on using spell combat or spellstrike all the time, is it best just to take things that modify basic attacks, or do you branch out and look for a secondary option to use when you're not spell-swording?
This was a very fun and effective build.
I didn't mean to say that half casters using traditional feat chains were bad, just that they eat a lot of feat slots. 8 of 13 feats dedicated to archery is quite a lot, and there were more good archery feats you could have taken if you wanted to.
I suppose you could pose the question "but what else are you doing with those feat slots" and that's kind of the question I had hoped to get an answer for, given my inexperience in this area.
This is a pretty broad category. Gallant definitely sums up a good archer magus for you, but half-casters do a LOT of things, and there are so many of them I'd struggle to list each of their individual needs.
Often many of these casters fit specific roles. Here's a list of stuff to give you some ideas.
Skalds, Bards and Mesmerists are pretty strong Charisma-focused support classes that can utilize their spells and supernatural abilities to augment their allies and themselves, and so can be built a huge variety of ways.
Occultists are known as the generalist class that can do practically anything you want with it. Casting, combat, skills. They have anything you would want, including being a full-bab martial (Trappings of the Warrior panoply).
Magus is more cut and dry, and requires you basically building a two-weapon martial without the regular feat taxes and more metamagic stuff. There are many ways to build a Magus, particularly given all the archetypes, but a magus is and foremost a martial and should be built pure combat.
Much like Magi, Warpriests are martials and should be built full combat, and can pull off a lot of difficult builds with ease thanks to their self-buffs, free feats, enhancement bonuses and action economy power.
Inquisitors are exceptionally broad, and while most of their abilities are selfish buffs, they also bring a lot of skill power to a group and generally can a good all-rounder, much like a bard. So you can't really go wrong so long as you focus on doing some combat stuff and some casting and skill stuff.
Alchemists are so broad, it would be reductive to try and tell you how to play one. They often focus either on ranged bombers or melee combatants using mutagen (Hyde is the coined term for them), and they have a metric f!**ton of self-buffing power to allow them incredibly broad capabilities. Their archetypes play havoc with this, making them really anything you want (including a better core rogue, actually)
Investigators, meanwhile, can do similar things but are also well known to be incredible melee combatants once they hit 5th level, and are exceedingly powerful beyond given proper preparation and builds. Investigators universally focus on building martial and melee, because most of their skills are improved through class features, but are very heavily Intelligence based and one of the few martials beside Magus who rely heavily on it for their martial power.
And Summoners are Summoners. They build to summon stuff (spell focus: conjuration, augment summoning) and their eidolon is built to be a full martial natural attacker. Done.
Spiritualist is very tricky given their archetypes, but I often see them recommended as utility summoners (without the summons so much) who deliver touch spells via their phantom, both for bad touch and general supporting. They are also great controllers combined with the Lust phantom or Jealousy phantom, and can kinda have their phantom do similar stuff to an eidolon though not as well mostly due to magic item restrictions and not as powerful scaling as a eidolon.
And Mediums.....PFFT, SURE, PLAY A MEDIUM. REAL FUNNY JOKE.
If you have adequate defences from the class and don't need to go dex-based then the simple answer is power attack & weapon focus or furious focus. Maybe combat reflexes if you're using a longspear.
If you're doing * grace or dervish dance it's a bit trickier. Piranha strike may help if you're using a light weapon, but not as much as power attack with a two-hander. Dirty fighting and a combat maneuver can work, or combat expertise & butterfly's sting if you have a buddy, combat reflexes & weapon trick (one-handed) can help and it's possible that a feat for your class named extra something can make a difference.
Craft magic arms and armor is a much underrated 'combat' feat.
TWF is not compatible with mild investment, and for archery to work with only a few feats you need class abilities or spells to boost it like explosive missile or named bullet.
A magus BTW will usually try to be using spell combat with arcane mark (or similar; my hexcrafter used brand) when they can full attack and don't have spells to waste.
I played a dwarf barbarian 1/magus 3 through 6 or 7, and he was very fun and versatile.
Traits:
Berserker of the Society
Magical Lineage? The -1 level metamagic feat for shocking grasp
Feats:
1. Combat Reflexes
3. Power Attack
5. Dodge (which was a poor choice since I lost it when enlarged)
6. (magus bonus feat) Arcane Strike
7. Intensify Spells
He wielded a dwarven waraxe, so he wasn't crit-fishing, but he could do Spell Combat, Spell Strike, buff w/ enlarge person to get reach and AoOs, rage and use two-handed Power Attacks, fail Diplomacy checks as agro (6 Charisma!), and use short-range blasts, like burning hands and color spray. It wasn't super powerful, but still very good and it was very versatile and a lot of fun and every fight was different and I didn't outshine anyone either. The level of barbarian was mostly for the speed boost, but it also added some fun class skills (Acrobatics, Perception, Survival) and It also meant I had to plan my spell-buffing and rage strategically, since he couldn't cast after raging.
I also played a half-orc inquisitor semi-switch hitter, and took Improved Initiative as my first feat. Going first helps buffing/self-buffing, and it works for melee, ranged combat, and spellcasting, and it doesn't have any kind of BAB requirements. I think his 3rd level feat was Power Attack, because half-orcs have Great Axe proficiency, and rolling d12s is fun. I forget what his 5th level feat was...he might have been eaten by an owlbear before he got there...