Fold equity you mean?

You should be able to make money consistently at all of them. Obviously, $20s will give you a higher return because ... obviously ... you win more when you win.

You should be able to beat both the $5 and $10 levels if you are a decent player. If you're losing at those games, you suck at poker and should rethink what you're saying. $20 SnGs aren't easier. Sure they're all easy, but $20s aren't easier than $5s.