What sort of content are you focused on?Void is probably the most versatile, but if you were looking specifically for defenders in BGs or AW, Misty Knight may be a better choice. Without knowing the depth of your roster, I'd probably say Void.
Don't go for void (if unawakened/low sig). 5.3 and 5.4 have paths like masochism, buffet, vigor, bane and resistor. Havok would probably be the better choice here. That said, I am a big fan of Misty and her ability to stay unblockable. It would definitely help transfer bane when the opponent is being passive and blocking. Plus, if you don't throw any specials, you could just stay unblockable and not need to parry to gain openings. Thus, ignoring masochism in a way.