Well, I'm excited! My H1203 is in Federal Way Washington and ready to board the plane to Alaska!

Later in the year I'm planning on buying a second H1203. My plan is to have a powerful modular system. I can use one or two cabs and a low or high powered head.
Now I'm on a quest for a more powerful head so here are some of my considerations:
GK MB500, GK MB500 Fusion--I like the Fusion option because I yearn for a good tube distortion like I used to have back in my younger tube amp touring days. QUESTION: Can the regular MB500 break up and distort like the Fusion?
Tech21 VT-500: If I don't get a GK MB500 I think this is my next choice. It is very highly rated and people love how the Tech21 can sound like an overdriven SVT. And that's desirable to me.
Mesa Boogie D800: This seems to be the high liner for users. A lot of satisfied customers and I see a lot of AK cabs with the D800. And yetttttttt.... I don't know why I can't warm up to it. I tried to listen to sound clips but everyone's too busy slappin and poppin and I can't tell how it would sound slightly overdriven. Wish I could.
TC Electronics TH550. I'm not as thrilled about this choice but I'm interested in all the patches you can use with this amp. I would be able to get just about any sound I want. That being said, I read so many requests for help because something is going wrong with a number of the TC heads.
Kustom 500 watt head--another AK cab buyer showed his rig a few pages back and says he loves the Kustom. Says it gets very loud. I don't know if it gets a nice distortion though.
So there ya go. I'm at a fork in the road. Which way to tone Nirvana for my new amp?