Kingdom Hearts would be a good one to start off with, then go get a GBA and play the Chain of Memories to add more depth to the story. FFX is really good as well since it was one of the first few PS2 RPG's
FFX is a superb Console RPG in the usual FF mould with a comparitively dark storyline.
FFX-2 extends the FFX storyline, but takes out all the darkness and makes it a Charlies Angels style game. The Job system in it is well done though.
Kingdom Hearts is an Action RPG and is quite superb at that. The only things that really let it down were the camera angles in certain platform areas were a pain, and it felt like it should have been a proper MP game like Secet of Mana or Seiken Densetsu 3.
Legaia 2 is crap. Take the worse VA you can think of in a game and multiply it by ten, mix in annoying as hell battle mechanics, and add a drop of the most boring and obvious plot you have ever seen in a game, and you'll still have a better game than Legaia 2.
Final Fantasy X is definitely worth your time and money; don't know about the rest, haven't played them. FFX has a unique story with lots of creativity, though I can't comment on how well written the plot is since I'm not good at that. The music is great (Nobuo Uematsu and some other guy) and gameplay similar to its predecessors. Only complain about FFX I have is the annoying English dub .
FFX yea great game loads of things to do even after u completed the game. 130 hours already.. and i still have a few things to do before i can beat the strongest boss/monster in game.
FFX-2 loads of girl power yea.. And imo the missions are starting to become boring.. and im only halfway chapter 3...
Kingdom hearts.. yea i would like to play that one myself someday
I loved Kingdom Hearts... but then again I am a huge fan of Disney. I thoroughly hated FFX and am repeatedly baffled by people's affection for it. I actually somewhat liked FFX-2 but the whole Charlie's Angels "girl power" feel to it was highly annoying. Haven't played Legaia 2.
Ok i love all three, ffx has great graphics and a great story line, ffx-2 alsoo has good graphics, Kingdom hearts is a great game and there are many fans of it, though the graphics arent as good as they could be the music is incredible, if you were to play kingdom hearts and beat you could go onto Kingdom Hearts: Chain of Memories on Gba which is the story of whats happening between the time of kh1 ending and kh2(which is still in works) beginning. (kh2 comes out around august)
I'm not sure about Legaia2 but the others are on the greatest hits collection. You can get those 3 for $20 each. That's a killer deal for FFX and Kingdom Hearts.
I would lean more towards FFX if you want depth and gameplay for hours. And Kingdom Hearts if you like the funny/serious stuff with decent gameplay. I couldn't really get into FFX2 that much, even with the 40 hours i've put into it. It's just not as interesting as FFX. Comparing it to Charlies Angels is an understatement. The first scene reminded me of that Spice Girls movie.
I didn't get into FFX; it had all the makings of a good RPG, but it just didn't do it for me. I have stated to grow out of games, and hooking up all the systems ended up being a bad idea (brother always pestering me, kind of kills any game), but I thought is was a little to stright forward, not enough "going out on your own" stuff; of course I didn't play for that long, think I just got to the thunder part with the caters.