I've been working my way by trial and error through bass amp heads and these are the sweeping generalisations I've arrived at:
TC - good, solid amps but the EQ generally positioned at the wrong frequencies for upright. Boomy and prone to feedback
Warwick Gnome - excellent value, but EQ bands in the wrong spots also.
Genzler Magellans 350 and 800- excellent for double bass. Even without an HPF, there's enough tone shaping to get you a decent sound in most situations.
Genz-Benz streamliner - tube front end actually slightly more flattering to an upright bass than the more modern Genzlers. Great.
PJB - Two Four. Couldn't get on with it really. It's very highly tuned to a single low frequency, so a real feedback hazard if you hit that particular note.
Traynor YBA300 - delicious, but heavy. Far too much low end unless you use an outboard HPF. But I do use one, and I'm currently in love with the sound of it. Just about sits neatly on top of an LFSys Monaco if you lay it on it's side.