opinion

For low elo, I'd say the jungler has the potential to be the most impactful throughout the game. You can snowball or at least prevent feeding in all of the lanes, and because low elos tend to suck at last hitting, the jungler has relatively more gold compared to the laners than in higher elos.

No idea about high elo, sorry :/

http://boards.na.leagueoflegends.com/en/c/tips-tricks/6WsI7eFr-bronze-in-2015-and-you

You're going to want to be probably a jungler or a hypercarry mid/top if you want to lower ELO carry

HIghers you're gonna want to look for more tanky aspects that bring the teamfight and push potential to the field.

Give that guide a read to figure out what exactly you should be doing provided you decide to do this.