Without a doubt: Monk.
Survivability, speed in killing and doesn't require too expensive or amazing gear so can be stacked with a lot of MF.
Not DH because I am certain they will be nerfed some time soon so not a good investment to gear a DH up with balanced gear since you have no clue what balanced is. Not WD because while speedy at killing bc of optionally great DPS just too fragile imo. Same goes for Wizard. Only alternative would have to be Barbarian but not the first choice bc it's harder (more expensive) to get the right build and gear for both defense, offense and MF.
Actually quite a good point.
Especially since we are going to see some changes in the MF-setup possibilites soon (tomorrow?)
(Easy) gearswitching FTW or possibly the opposite? Last week I thought they were going to patch the possibility to switch gear just before a kill by taking away the NV but now reading Bashiok's comment on the subject there might be a gearswitch button soon? :o
Lame and completely unrealistic imo but it could give a number of players that extra push to be able to find better gear.
If it (or something similar) were to be implented soon I might actually start using it the other way around:
Always run around in full MF-gear and switch to dmg/prot-gear when encountering some nasty pack or boss..