Being too powerful (like Surfer) wouldn't be fun. How the hell would you ever really use power cosmic?? It's not like we actually exist in a comic world. A GL ring (or Alan Scott more likely) would be awesome...but apparently (after the slight retcon in GL: Rebirth) it hurts to use the ring....emotionally and physically. Maybe Alan gets around that.
Otherwise, yeah Deadpool's healing would be awesome. Or Longshot. Or Spider-Man, or He-Man, or (many others).
Also moving...
Multiple Man's powers compared with Mystique's. I would create a dupe and ask it to transform into a woman...😖hifty: Also, compare that with David Alleyne's powers (but I would not forget the skills). I would go next to all the business geniouses, inventors and other professionals. Then I would create like 200 dupes, and form my own multi-international company that would excel in anything and would have unlimited amount of workers. Who would work free.