Personally, I think Fighters are way better than Cavs. Someone said that Rangers and Paladins are the best martial classes and questioned why anyone would ever play another martial class. There are many reasons not to play a Pally or Ranger. Pallys are overly reliant on 1 or 2/day abilities like weapon bond and smite. Also, you're forced to play Awful Good if you're a pally. That may not be for everyone. Rangers core abilities (Favored Enemy, Favored Terrain) require alot of guesswork on the part of the player to make them useful, and if you guess wrong, you're hosed (you took Orc as favored enemy? No orcs in this campaign, have fun sucking!). Also, the combat styles force you into very specific builds, which may not jive with everyone.
Personally, I hate both pallys and rangers with a passion and would never play either. I'd play a Fighter though.
Even though I love Paladins and it's one of my favorite classes and I'm in the minority on loving the Lawful Good alignment restriction, I understand the complaints and have no argument. BUT I think you're way off the Ranger v Fighter thing here.
The Ranger's combat feats are actually more freeing than the Fighter's bonus feats because they don't require prerequisites. For instance, all of the best Archery feats have minimum Dex requirements or that you take other feats you may not want. Ranger gets to skip right over that. For that matter, the Ranger can go TWF without sacrificing an ounce of damage output --- the fighter will HAVE to sacrifice STR for DEX if he wants all of the goodies.
And while the Ranger picking the wrong favored enemy can suck, you get additional ones to choose after you've been playing for a while and even WITHOUT the feature, Rangers still do a fair amount of damage. And have way more skill points. AND spells. Including this one, that will ultimately make the whole wrong favored enemy selection nebulous in actual play.
That being said, I don't think most people say Rangers/Paladins are the only martials worth playing; not while the Barbarian exists, anyway.
The Cavalier needs far more love than it's given. A mount is a pretty powerful option, but it's also way too easily shut out by a petty or unaccommodating GM - especially compared to an Animal Companion, which is still near its max effectiveness when it's not being ridden.