Fallout 2 ! the first is really playable with Dosbox Turbo on Asus Nexus 7. But Fallout 2 has no DOS version Only Windows. And like my predecessors i think it would be great to have Age of Empires 2 and Pharaoh on android =).
My vote is for diablo 2 Lord of Destruction if possible, if not diablo 1 would work for me.
P.S. For those of you asking for Heroes of Might and Magic 3, there is already a free app that allows you to install your copy and play on your android device (although with some bugs, but still highly playable). To play HoMM 3 download VCIM on google play To play HoMM 2 download Free Heroes 2 on Google play (even comes with free demo so you can jump right in and play all scenarios)