Depends on what you want. Dark Cloud 2 is a little light on the story department, its a bit of a cliche tail and rather simplistic...but it does have its charm. DC2 shines more in the gameplay and weapons department. Its action based with one of the deepest battle systems of any of the action RPG games. The main charcter can attack in a few ways with his main weapon or attack with an offhand weapon. Then there is the alternative charcter to play as who again has several moves a back flip and a distance weapon. The second character can change into monsters in addition, while the main character can climb into a giant customizable robot(change its weapons from boxing gloves to missile launcher to guns or its lets into a hard to turn but fast motorcycle or extreamly agile but slow helicopter bottom). The characters don't level up, instead weapons you attack with gain points that you can use to break items into spheres that are then fused into the weapon to offer bonuses like atk up or elemental attacks. Each weapon then has branching paths of evolution that turn it into different weapons. In the end the branching paths lead to 3 or 4 ultimate weapons each with their own pros and cons(though you can ultimatly break weapons and fuse them together to make a super weapon that will have all the attributes).
If you want action and something with a deep level/weapon system grab DC2.
FFXII I couldnt get into but its not horrible. I just felt the story didnt go anywhere, the characters received far too little development...and the battle system was not quite action not quite turn based.
Suikoden III I cant reccomend. It has a great plot but its battle system is borked.
That leaves Shadow Hearts. Shadow Hearts I dont recommend......but Shadow Hearts Covenenet is freaking awsome. And you probally want to play Shadow Hearts before playing Shadow Hearts Cov. Shadow Hearts isnt a bad game it just hasnt aged well. Its story is just ok most of the game and there are not really many things to do in the game outside the main plot which really leads you by the hand. The graphics also havnt aged well. THe battle system still kicks ass though. Whenever you choose to do anything in battle from attack to use items a clock looking circle pops up. Now imagine that the clock has several parts lit up in the shape of a slice of pie. The hand of the clock swings round and you have to stop it in that slice to accomplish anything. If your charcter attacks they can attack 1-3 times based on how many of the slices you managed to hit. And instead of critical hits being based on luck its based on skill. At the very tip of each slice of pie is a very tiny glowing red area. If you hit that area then that hit is critical.
Shadow Hearts Cov takes SH and kicks it into overdrive. The story is freaking awsome, there are more cut scenes to boot and its really got length to it. The battle system is also improved, it takes the first games battles but then adds in combo attacks with other charcters which can REALLY up your damage....however if the enemy breaks your combo you can really miss out. It also adds in the abilty to find new peices for your ring which allows you to go from hitting 2 times up to 5 in battle.
I LOVE Shadow Hearts Cov and it seems most others do too. So if you want a traditional RPG with a twist its a great buy....but you should try to have the money and patience to play through Shadow Hearts first.