Look at the stage of any major rock band from Fleetwood Mac, to Nickelback, to Slayer. A LARGE majority of the times you will see a very limited list of different amps. Mesa Rectifier's are certainly in the top 3. None of those other amps, save Marshall, fender, and a few choice Vox, are anywhere in sight on that scale. I promise you that if you can name a major artist that uses Valve Kings that they have an endorsement deal, and they are more than likely modded. Fact is, Mesa is a well respected, widely used, professional piece of gear. You may like the tone you get, but the argument that it's "crap" is simply not winnable, and is really just kinda ridiculous. Go to a bunch of major studio's and count how many Mesa's, Marshall's, Fender's, and Vox you come across. Then count the number of Peavey's, Crate's, and V3's with 8" speakers you come across. There are respected professional industry standard pieces of equipment, and there is the armature B list.
So, I stick by my original statement. When it comes to your guitar rig, buy pro gear so you only have to spend the money once. You really take a beating on resale on the B stuff.