Depends on what you are farming, items=barb, gold=demon hunter, unless gearing funds are unlimited the you could realistically outfit any class so that it could work. I have a barb for act one, he is nearly able to do act two by not quite. I have a dh that does hell mode act 1 and make 250k ish per hour (300gf unbuffed) and never die I pick up every thing and vendor it unless it meets some very stringent rules). Pretty much all I keep are legendaries on NM. I keep all tomes of secrets and more items on Inferno, a nice niche is leveling gear and keep a constant stream of items up, at a reasonable price even 2 stat gear sells very well for leveling.
But really it doesn't take much to be able to farm Hell, so any class could be outfitted pretty inexpensively with as much GF and a decent amount of main stat plus vitality.
That being said I'm not really farming for
$. I enjoy the social interaction and have a DH, a WD and a barb that are geared as well for Inferno as my friends are, and I make well enough so that I can give them a few million gold every week. Our social interaction is enough to enjoy enough the challenge of 3-4 manning Act 2-3 Inferno. Also we're anticipating a lot of fun when pvp gets implemented. And there is always our level 50 ish Hardcore toons we've been leveling (mines a barb sheerly because he's tough as nails)...