If I'm doing my music, I use the guitar and amp that makes the sound I need. Size, watts is not the question. It's what makes the right sound. Could be a Marshall 100 into a 4x12, could be a Hiwatt where everyone has to leave the room, could be a Fender Champion 600. Might even use a SansAmp or Line6 or Zoom if it makes a particular sound better than anything else. Depends on the songs being recorded.
If I'm playing on someone else's music, I'll pick something more versatile because I never know what direction I can be hit with once the first couple passes are recorded and played back. Like "That sounds too AC/DC, can you make it more U2?" which means I need to be able to flick a switch or press a button and change my whole identity. For those situations, I'd use like a SansAmp into a clean Vox AC30 or Fender Twin (amp is just a PA but tubey to warm it up and give it a speaker/room sound for good vibes). Also I'd keep more pedal choices handy if I don't know what the artist is going to come up with on the spot.