#1 was sooooo obvious. Hell, I would be surprised if it wasn't #1. As easy as it is, it was the first metroidvania and it is the only game that actually stars Alucard. I would commit five atrocities in order to get another game staring him. I exaggerate, but you get how I feel. I'm pretty sure a lot of us on this forum have similar feelings.
Getting back to the list, I surprised that OoE wasn't higher.