Smilzo
Fractal Fanatic
Then again a tube amp and a SUPER LOUD tube amp don't have similar attack. I'd say the super loud amp isn't as tight as one with volume down and I think POD HD is modeled more like a super loud amp. This is something you can control in the Axe-Fx.
You talk about poweramp vs (hi-gain) preamp distortion. I love to blend the two. In real amp I choose the core of my sound in the preamp, than add flavours listening to different level and tweaking preamp distortion. In real amp, I have different output level for different preamp/poweramp balance. With axefx it is possible to match them in level.
If I were L6, I'll model the tube amp on chosen magic balance, not on crancked master.