i would say akali, i have won many 1v1's as akali and 1v2's against two people my same lvl.

Nasus>Tryndamere>Everyone else 1v1

For 1v1 AD melee I would say Jax is pretty effective.

Nunu is pretty good. Harass, eat minions

I would think Warwick, jax, tryundamere, yi.

yi or poppy

or mundo

Yi, Poppy or Kog'Maw

nasus is a pretty effective solo mid imo, if you play by the first tower/death rules, just push like mad with spirit fire from the start. and with siphoning strike hitting the tower, it'd be fast. lvl wither if you want, but i usually take exhaust anyways

Poppy is very strong 1 v 1
And 1 v 3