i wouldn't want anything capable of rupturing space-time, but I would want to be powerful enough such that pretty much no one could defeat me
always been partial to Hunter X Hunter abilities just because they're so strategic
Hisoka's abilities would just be great. Using Bungie Gum to it's full potential is incredibly formidable, and then, as a sort of side ability, being able to change the appearance of any text or inanimate object is quite cool too.
I wouldn't want to go full out Enel with electricity powers, so I'd probably pick Killua's abilities; recharging with an outlet, short bursts of super-speed and small electric shocks, etc.
Although, I think upon reflecting over this for a long time, I'd have to go with Aokiji's devil fruit. Being able to freeze absolutely anything is god-tier, but also the idea of biking across the oceans (freezing any incoming storms and waves) is too romantic to pass. I mean you do get the down-side of not being able to swim anymore, but I think Aokiji, with the level of mastery over his fruit that he has, doesn't really see drowning as an issue; the sea is still pretty much free reign for him