If you can find a copy of Hexyz Force I would recommend it. Bought on PSN for $3.50 and its awesome. Also like others have said Persona 3 is a must.

Others I like are: Flatout Head on, Gran Turismo, Race Driver 2006, and Persona 2.

Got the PS2 collection of Liberty City Stories and Vice City Stories, but I do have to pick up Chinatown Wars.  I keep forgetting about that game for some reason.

Other choices according to your game collection:

-Metal Gear Ac!d and Ac!d 2. Great games, its a turn card based metal gear. I liked them more than Peace Walker but thats just me

-Final Fantasy Tactics if you havent played it on PSX, my favorite FF game

-Syphoon Filter. GREAT game, a must buy if you like action/stealth games.

-Gran Turismo if you didnt play GT4 of PS2

-I really liked a RPG game called Kingdom of Paradise but its not for everyone tastes and its one of the first PSP releases

-If you like Guitar hero or rockband and DDR type of songs, try DJ Max Portable, its pretty good. Very addictive

-I do not reccomend Tales of World, its pretty bad compared to other tales of games

-Jeanne D' Arc, Tekken, Persona 3, Castlevania, Monster Hunter(its damn hard), Exit +1

Whats wrong with Tales of World, please be as detailed as you can.  There's not a lot of reviews of it online and I have no friends that play the Tales of series. 

Wow I completely missed thread.

Tales of the World gets boring fast to due repetitive boring quest

I only played the first one(I think there is 3 of them), first I didnt like the story, very generic, slow phased, you dont get "I need to keep playing to  know whats going next" feel, RPG stories need to be at least good to keep your atention. Gameplay is good(but its semiauto, sometimes just button mash), I liked it, battles are like other tales of games, colorful. Characters are not very enjoyable(Some funny dialogues are good every now and then), they do not develop  very well, but there are characters from previous Tales games, so you get some fan service(meh for me). Music I cant remember. Gaphics were good for its time and platform.

In conclusion, its a ok game, bad compared to previous Tale of games(for me), and there's better RPGs to play on PSP to use you time on this one(IMHO)

Final Fantasy IV Complete Collection.. It's just perfect fot the PSP. I highly recommend it for any rpg fan.
Persona 3 Portable. Nothing to say.

Final Fantasy Tactics The War of the Lions. One of my favorites FFs.

HALF-MINUTE HERO. This game doesn't get the love it deserves.

Brave Story New Traveler is a pretty fun rpg.

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