Crazy I've been listening to T-Pain albums lately. Dude made some great songs & guest features.
Out of all 4 of the options I'd have to vote for him mainly because the other 3 guys had their runs virtually uninterrupted (Ja Rule was already tinkering off when 50 came.) Pain's run was cut short due to an oversaturation of imitators and Jay-Z's playa hatin'.