There is no magical, best, easiest character. Every one of them has their pros and cons.
Fishy: Pros: Walking tanks that can obliterate anything in their path, Almost never taking damage personally. Cons: Boring after a while, Too much white is hard on the eyes sometimes.
Hammerdin: Pros: Massive power that is hard to resist (Horadric Mummies and Plague Bearers are the only ones who are immune, I think), Only spellcaster that can constantly keep his merc powered up (Amp doesn't count) Cons: Mana intensive early on, Hammers are hard to aim at first, Can be gear dependant.
Meteorb Sorc: Pros: Powerful even with limited synergies, Common as a MFer. Cons: Also can be gear dependant, esp. for + to mana and + to max mana items, Hard to start out as with no meat shield.