Gonna break this down into ones I've played and ones I've heard good things about.
Played:
Dark Chronicle - Shallow as hell combat 'system' but tons of stuff to do. Random dungeons also. Love it.
Suikoden V - Found this really compelling despite the slow start. Lots of characters to collect.
Breath of Fire V - Weird. It's sort of survival horror'ish in that enemies don't respawn, there're no inns and you have limited saves plus an irreversible GAME OVER countdown. So you can't grind and it's possible to get to a point where you're complete fucked. But there's a 'restart anytime' option that lets you carry some stuff over. Difficult to summarise effectively, so look it up.
Grandia II - Standard stuff, but good battle system and (some) decent characters.
Heard good things:
Valkyrie Profile 2 - Seems incredibly polished. Watch a video or something.
Dragon Quest VIII - Traditional RPG done well apparently.
Final Fantasy XII - Meh.
Ar Tonelico 2 - People seem to dig the anime/VN influence.
Might be worth looking at:
Megaman X: Command Mission - Surprisingly polished and enjoyable.
Odin Sphere - Beautiful game world/scenes/bosses. Repetitive though.
Shadow Hearts Covenant - Generally held in high regard.
I'd mention SO3, DDS and P3/4 but I know you've played them. Nocturne is the best SMT game so get it if you haven't already and you can actually find it. If you want to play a NI game get Phantom Brave.
I would suggest Xenosaga, but it doesn't seem it's out in your region, which is unfortunate. Wild ARMs III isn't...Too hard, but it does involve quite a bit of grinding and exploration (good luck trying to get all the EX Keys without a guide).
We got Xenosaga II, but it's pretty bad. We got WA3/4 as well, though I've played both and wouldn't recommend them to others (despite enjoying 4 quite a bit).