I'm using a matrix GT1600FX into a Mesa 4x12 slant with celestion century vintage speakers. I've had this cab since 2007. I knew nothing of speakers when I got it, its just what came with the roadster I bought. I'm used to hearing every amp through that. There are so many cabs and speaker combinations that there really is no best, just what you like. I'd narrow that down maybe based on the IRs you're using.
Power amps you might see on the forum
Seymour Duncan Power stage (solid state, comes in different watt configurations. It has tone controls)
Matrix gt series ( solid state, different watt configurations, stereo and mono mode. No tone controls)
Fryette power station (100w tube, there are a few models with different configurations, fx loop, presence and depth controls)
I've only used the Matrix stuff and the FX loop on my Mesa Mark V so I can only comment about those. The matrix allows me to keep power amp modelling on and let that shape the tone and response on each amp model. It sounds good both loud and bedroom levels. It is lightweight and can be had as small as a 1u rack space. I have the GT1600FX so it is 2u.
Keep in mind, with any combination of this new setup, you'll have to rework your presets. Don't plug and play with your current patches minus the cab block and expect to be blown away.