Vice city is most definitely the best of the three later GTAs. San Andreas just didn't do it for me. The ghetto vibe and the dull colours made it hard to focus for me. Whilst I tried to play Vice City through to 100%.
I didn't really like FFX-2, thought FFX was much better, especially if you tried to max out things like the monster arena and the dark aeons.
I have quite a few PS2 games and most find themselves played for a few hours and then tossed to the side, the exceptions that get played to the end have been:
Final Fantasy X
Devil May Cry 3
Gran Turismo 3 and 4
Grand Theft Auto: Vice City
SSX 1,2,3
Metal Gear Solid 2 - Really not a fan of 3. The jungle environ sucks big time and its too hard to see guards.
I have not come across a good FPS on PS2. FPS more designed for a pc imo.