'Best' for me is a combination of factors, including weight.
The PJB M-500 was hands down the best sounding solid state amp I've owned (as long as it wasn't going through PJB speakers), but my TechAmp Puma 500 does the job and is a lot lighter and quieter.
My favourite however, is the 100w amp in my Peavey Vypyr VIP3, which contains Electric guitar, Bass guitar, and Acoustic guitar amp models, and is actually loud enough to do a large pub sized gig on bass.