I’ve owned and gigged a good few all-valve heads (‘70’s Orange 100W, Fender Bassman 135, Ampeg SVT-2, Trace TwinValve, and Mesa D-180 - I still have the Mesa mainly as it doubles as a guitar head.....) but has been said many times on this forum; it’s darn hard to beat the valve tone and sheer practicalty of the Mesa Walkabout (a 300W hybrid amp of course). Mine is my go-to head unless I’m playing funk, in which case it’s the Ashdown MK500.
Having said that, I’ve never tried the Handbox, heard very good things.