The Zero Escape series, it only had one OVA but it was so good. I wish they continued it.
Recently started replaying the first Soul Reaver in the Legacy of Kain series of games and with how the lore is told and how the world is built, I can definitely say a Legacy of Kain anime would be kickass! Would love to see one for Darksiders as well, the crazy art style would be perfect for that kind of medium.
I would watch Dragon Age the anime
I'd say Mega Man Zero.
Based on how the japanese commercials looked, I think it could be promising.