Hoo-boy, that's a difficult question.
Out of RPGs I've played, the ones whose gameplay jumps out at me the most would be:
- FFT. The only problem I have with it are ridiculously small map and party sizes; there is of course Tactics Ogre for that plus interesting weather effects and undeads, but FFT's combat and movement is done smoother overall, IMHO.
- FFVII. I simply dig what can be done with materia; unfortunately the majority of that is just for fun, left unexplained, is unnecessary to learn and is easily missed.
- FFX. I've liked the handy initiative counter, the ability to switch out characters with the 'back row' (it worked so good that I've even felt I was cheesing the game), the ability to develop and set different modes for the overdrive gauge depending on what this character was actually doing , the awesome pokemon-like summon battles and the way the game handles the enemies' vulnerabilities to different methods of attack. Unfortunately it had somehow resulted in fighting (what felt like) pallette swaps of the very same enemy party every goddamn time, Kimahri having no role in combat whatsoever and hp-sponge-one-hit-kill-spamming bosses. The combat system still left a very good impression overall though.
- Gothic. Can't say that I've like the fighting very much, but the first two parts gave a very good impression of genuinely scary enemies. The third one had some good action because it had finally allowed you to hit muliple enemies with your swing if your weapon allowed but was 'meh' in all other respects. Didn't ever play the forth one or the Risen I&II 'spiritual successor' so can't say anything about them.
- In Skyrim I had the most fun in combat out of all the Elder Scrolls games by far. Unfortunately it lacked the mighty :pirate: kick of the Dark Messiah game (which is even less 'RPG') to unleash whoopass for real.
- Persona 2 had a very neat way to adjust your partymembers' order of action, manipulating which was required for the nifty spell combos you really needed in order to clean up the dungeons in a cost-effective way. It even remembered all the combinations you've already used in the current playthrough for you and quickly showed whether your current party/pokemon roster could use the combo you wanted and who you needed to swap if it couldn't. Can't say anything for other Persona and/or MegaTen games - I have yet to try them - but damn if I'm gonna play any of those without a guide though :biggrin2:.
- I absolutely love Front Mission 4 and 5 gameplay. Unforunately some maps are simply way too flat for the fun combat system the games provide and the way enemy linked sqauds work was intentionally nerfed barring that bonus mode for New Game+ in 5. More allies/enemies and non-mech units would've been nice too.
- Super Robot Wars and all its ilk is just pure :pirate:. The boss fights tend to be waaaay too much hp-spongy for my taste though.
That's just what I can think off the top of my head, there is probably more.
As for Xenosaga, my most favourite combat would be the one from Ep. II.
In my opinion, mech combat was done the best in Ep. I; it also had the Cyberkick, Blaster and R-Cannon, branching (customizable and upgradeable!
) attack tree that I happened to dig very, very much. Ep. III has dropped that roulette-reel that existed with the sole purpose to screw you over with a bunch of random criticals and made 'special' weapons Ziggy and KOS-MOS can wield something more than a complete waste of turns;
I have certainly liked (and abused the hell out of) the break gauge.
I still like Ep. II's combat the most, me completely missing double-casting via boost until I've looked into a guide for that Margulis fight tips notwithstanding. The majority of combat animations looked better in that game too. (Not the sounds though - firearms are a complete pew-pew toyshoot there).