Personally, I'm going with Rogue. I own the entire X-MEN Legacy series & I have to say, Rogue having full control of her powers during that run with no permanently retained powers is phenomenal. Love how much potential she has with her mutant power alone. She even beat the Avengers the second time around.

Would the absorbed powers be temporary or permanent?

Temporary. But she's would use the power better than the individual she'd absorb from.

Absorption

IRL? I'll go with Jean's. There is no power to “Temporarily” absorb from.

Absorbing powers that require touch is very limited you need to get close to your enemy to acquire their powers that's if they are stupid and don't kill you immediately god help you if they fly how would you reach them

Telekinesis and telepathy are extremely powerful if used properly so this is my choice