Although an amazon could kick ass and get to the top, I really don't give a shit about being at the top of the ladder, I'm gonna MF like crazy and get tons of the "Ladder only" items and then sell them on Ebay once the ladder season is over or something.
For ladder running solo it will be hard no matter what char u choose but i think anything with added life like a barb will increase ur chance of survival but xp might be alittle slow
sorc is good for ranged with orb so may compensate for crap eq & probly low life too