There are several excellent choices for the Axe IMHO.
I have used extensively, and highly reccomend all the following:
VHT 2/50/2 .,....Probably my favorite of the bunch, but I would be perfectly happy with any of them.
Randall RT2/50...great, VERY flexible power amp. My only issue is the fan is noisy, but you can replace that.
Mesa 50/50...Excellent 6L6 tone
Carvin DCM600..... I know this isn't tube, but it is a great amp
Haven't used the Mesa 2:90 with the Axe, but have used one before and also really like it and can't imagine it not sounding great with the Axe Fx.
I also used the QSC monitors and while I prefer using a power amp and cab (or 2), I thought they did a very good job.
The only thing on my GAS list right now is one or 2 of the Fractal powered monitors. I am really looking forward to trying them out.