Second Mesa became first choice
I own several amps: Fender Twin, Hotrod Deluxe, Mesa Mark III. My choice has been the Mark III until I got the 5:50 +. It is easier to dial in the sound I'm looking for. The sound is very close to the Mark III and after the band gets to cooking, no one can tell the difference.
I play mostly country so I'm after a very clean tone. I get this with a John Deere thrown in just for good measure. Just can't beat it. If I need some dirt, I use my pedal board to grab blues and old time rock things.
The only down-side: it is physically bigger than I wish. The weight is not that bad compared to the Mark III or the Twin but the size makes it clumsy and awkward to carry. If it wasn't for this, I would rate this at a total 5! It is a great sounding and amazingly versatile amp.