well.. like ff is difficult..

in ps1 you can try legend of dragoon.. an awesome rpg game

chrono cross, grandia, legend of legaia, they all have a graphic more like an anime than ff series, but have also a good story

in ps2

xenosaga (1,2 and 3 - you should play in order)

persona 3 (have a bit different style than ff but is cool either)

grandia3, suikoden 5 and dragon quest 8 I played and liked. but still think that ff is better.. (matter of preference i think)

star ocean 3 i found it very good, but has more action than ff series (fighting you control the character)

and now i'm wanting to play valkyre profile 2 and wild arms