For something close-ish to Kingdom Hearts... Dark Chronicle / Dark Cloud 2, maybe?

Cute little 3-D action RPG game with masses of content. I didn't play a lot of it, but it's meant to be quite good.
For PS2 RPGs I generally really like... Breath of Fire V, Xenosaga series, Wild ARMs III and V (and IV to a lesser extent), Shadow Hearts series, Mana Khemia, Tales of the Abyss, Ar Tonelico series, Suikoden III and V, Persona 3 and 4, Shin Megami Tensei Nocturne, Ys: Ark of Napishtim... Stuff like that. Though to be honest, you can't really go wrong with most RPGs on the PS2. A few dodgy early efforts aside, the quality of RPGs on the console was generally very high.
