5. final fantasy xiii (sure its linear, but the combat cant be beat )
4. final fantasy xii (combat is a little wanting, but boss fights and quickening chains are amazing. there is no enemy in ANY other game that takes as much skill and time as yiazmat.)
3. fallout 3 (for sheer size, im 100 hours in and still not done exploring)
2. oblivion (for sheer size and depth of the story lines)
1. final fantasy vii (most people who've played it will say the same. best storyline, best action, and incredibly large for a ps1 game. also boasts the largest collection of sequels and prequels of any game ever made. if you havent played it, you cant say you are a true fan of rpgs)