Twist...welcome to the community.
There's guys on here like Budda or Govtmule that are more up on this I am. Even though I play rock with my touring band I also do jazz and blues when I'm hanging out locally. My Fuchs covers all these well although I'n still searching for a Dist pedal to put in the lead channel to give it that really extra umpf...think EJ's solo in at the end of Desert Rose.
The Fender or the Marshall? I know a little about both but unfortunately not a bassman or the Marshall 30th Anniversay combo, If it were a Fender Super Reverb I'd say go for that in a heartbeat. It has fantastic clean sounds and handles pedals very well.
What kind of out board gear are you using? What pedals/effects? The Bassman is a single channel amp that's pretty clean. You'll have to rely soley on pedals for any OD/Dist tones. I don't even think the bassman has verb on it.
The Marshall is a 3 channel amp and from Marshall's website:
Summary of 30th Anniversary Features
Original models 6100 (head) and 6101 (combo) made in blue vinyl during 1992
Subsequent year models received an "LM" suffix and were produced in black vinyl
Three channels, each with selection switches
Channel 1 (mid shift and bright)
Channel 2 (contrasting crunch modes)
Channel 3 (gain boost and mid band contour selection)
Channel switching by footswitch, midi control, or from front panel switches with LED indicator)
Sensitivity switches, one each for low or high compensation, to match guitar pickup
Power control allows high (4 valve, 100 watts) or low (2 valve, 50 watts) mode output
Pentode or triode mode operation in either mode gives effective power range from 100 down to 25 watts
Power amp damping control for tighter sound and fuller distortion: high, low, or auto.
Auto mode damping pre-selects the right damping to the correct channel
Comprehensive effects loop provides level control, series or parallel selection
Separate send level trim: one each for clean and overdrive channels (-10 to +4 each)
Balanced output with level control features authentic compensation for a real direct to board guitar sound
Impedance selector
NOTE: The 6100 series amplifiers do not have built-in reverb
After reading this, The Marshall seems the way to go. Sounds extremely flexable and wide ranging. I might look into one myself
Good luck!