I would Like to have Champions Strength and Immortality and Psi-Lords telepathy powers and Juggernauts powers and Gladiator Flight speed and Thanos I.Q lol
1) Pre-crisis Superman
2) Silver Surfer
3) Photon
4) Sentry
5) X-man
6) King Thor
7) Longshot
8) Thanos
9) Captain Marvel (DC)
10) Kenshiro from The Fist of the North Star
Any one of those guys powers would be great to have but I would give them all up, yes all of them, for the Infinity Gauntlet.
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).
Multiple Man's powers compared with Mystique's. I would create a dupe and ask it to transform into a woman... 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.