The real world stipulation kills all of my favorite powers basically unless we're considering telepathy a real world power.
From what's left, I guess I'd go with peak human(or as close as possible in the real world) physical attributes and skill. You could smash straight through ever major combat sport and probably go down in history as the greatest fighter ever. Money wouldn't be a problem either.
Super intelligence is also nice, but it seems like more work.
Ibwas thinking about the op...
Since real world and comics don't really mesh... I'll put what low level non herald power I'd want... Like meta or less..
In that case I'll go with someone like wolverine or beast without the claws... Extended life, strength speed etc...
I thought about Luke cage for a second but he'd probably be "too" powerful...
People picking toaa mm or beholder I think aren't trying to do what intention of the thread...
... Or some kind of low level technopath... Dear ATM machine... Please give me 100.. Thank you. I mean as long as you don't abuse it...
going by real world physics and biology only animal themed powers like 'super'hearing and poison glands or enhanced physical and cognitive performances would be possible. for the most part, they'd peak at low or mid meta levels. telepathy would be a definite nono.
I'll take uncharted regeneration of tissues - instead of our lame cicatrization process - as fast as it can possibly go irl and a prolongued lifespan. So basically, a toned down healing factor which is in line with what some real world organisms are capable of.