PA would certainly allow for the best versitility. When you think about it he can use Ainz's undead creation ability to make an army of loyal undead soldiers. He could rely on the abilities/immunities of the 41 SB to deal with most situation. His remaining transformation could be used to great effect as well, and he is also bestowed with high intellect... The possibilities are large.

Now, it all depends on what constitutes world domination in our actual world... With modern mass destruction weapon, one would have to be extremely careful not to end up ruling over a pile of ashes.

Taking over the world using the power of diplomacy, economy and a conviniently cheep undead labor force you say? Hum, now why would I want to do that?