Stay out of Borderlands, it's more of a dull FPS rather than a good RPG.
Fallout 3 is super fun and it should last you ages, especially with all the DLCs, I'd recommend that.
Oblivion is also a great choice, it's pretty similar to Fallout but unique and fresh enough to warrant a purchase.
Stepping out of the rpg element, I can't help but recommend Heavy Rain, especially since you enjoyed Indigo Prophecy.
Oh and if you still have a PS2, you need to get Persona 3, it's a really really fun jrpg that combines turn based combat, dating, colecting demons and fighting/ using them. It's pretty versatile and while it might not sound like something you'd like at first, it's REALLY good. Hell, I had never played a jrpg before this one and I just loved it to death.