Mesa Boogie Big Block Titan V12

IMO, the single best Hybrid amp built to date. The amp has power for days; I play in a metal band, our guitarists each have a 120 Watt Blue Voodoo head into a 4x12, the loudest drummer I have ever played with, and I have the master volume on 2-2.5 (0 is at 6 o'clock, I am slightly over over 8 o clock) and channel volume at about 50%. (head runs into a Mesa 4x12). Still I have to be careful to not overpower the guitar rigs!
Besides the gobs of power, the semi-parametric allows for excellent tone shaping, without going overkill. Perhaps my favorite feature is the built in tube distortion. It adds a natural, organic saturation to the sound and can go from a bit of dirt to all out over the top fuzz/distortion based on your use of the OD volume and level.

Tuner out, slave out, included footswitch, this amp is a great package. They were a great value when new, at the current street price for a used version, they are an absolute steal!

The Mesa Titan V12...... Well.... The name says it all. Two fully independents channels with their own overdrive. It's simply 2 Big Block 750 in one amp. The sound is close my M9, with a little influence from the M-Pulse or the BB750. The Titan clearly sits in between, but to me, leans toward the Carbine series. Massive, clean, clear tone, to over-driven, fuzzy, old-school tone. The power.... just deafening. My SVT 4 Pro pushes a damn amount of power, but it feels the Titan is even stronger.
You can use two completely different instruments and switch between them thanks the great A/B box. Everything can be controlled via the 5 button footswitch. The amp is way lighter than the SVT 4 Pro. It's about the same as my M9. Pretty convenient though.
The only thing missing? The great Mesa compressor you can find on the M-Pulse 360/600 and Carbine M9. But I guess the head was complex enough for Mesa to add such a feature.
I you need complexity, dirt and massive sound go for the Titan (or BB 750), if you just need clean massive tone go for the M9 or the SVT 4. The Ampeg is still a great competitor to the M9, I own both.