PDI09: not bad, needs a load, lots of "funny" mids. PGA04: tweakable, still some funny mids, mucho bass if needed. No load needed.
Marshall SE-100: very nice old unit. Sounds like a Marshall, typical upper mid-thing. Not bad if used into a modeller with its cab sims IMO. No load needed.
RedBox: ?
Behringer: ?
Newer Diezels like Einstein have an emulated out. Holds up to any other external emulator well IMO.
I usually use a Behringer GI-100 in small gigs. I think that for its' price is unbeatable. It does need external load (cab/dummy load), but sounds pretty good (has a built in 4x12 cab simulator).