That Mesa Mark V 25W mini head sounds more than good enough for recording and practicing at home studios. If you guys think that's not even enough, I can't understand that...
It's fine for what it is, but a 25 watt amp, including that one, usually has limited headroom. That can be either an advantage, if you want to overdrive an amp early, or a disadvantage, if you want a lot of dynamic range clean or overdriven.
Certainly it's good enough for practicing or recording. What isn't? We all know stories of artists who used very small amps to great effect on classic records.
But the question of whether it's going to give a player the tone he or she is after is certainly a personal one. And of course, everything depends on a player's technique and expectations about how an amp will respond to our playing.
You compared it to the Mark V 90 watt amp, an amp I'm very familiar with since I owned one. The 90 Watt Mark V, at full tilt, can produce tones that can be heard on recordings that the 25 watt version can't do. However, the 90 Watt Mark V could also be switched down to as low as 10 Watts. So there is an advantage to the larger amp, it's simply more capable.
My Lone Star 100 Watt amp can do things that the Lone Star Special, a 30 watt amp, can't do. It can also be switched to 50 and 10 watts. So I think the advantage is with the higher power amp - it has much better headroom than the Special. And that matters on both clean and dirty tones.
Again, that may not be what you want, but I think it's an advantage to have that capability.
For that matter, before I had my 30 Watt HXDA, I had a 50 Watt HXDA. The 50 could do things the 30 can't do, and there are many sessions I do when I wish I'd kept the 50. It could drive a speaker cabinet differently, and it was a bit more expressive for that reason. It had a looser, "about to bust loose" feel that the 30 Watt version can't touch.
When it comes to small amps - clearly that's today's trend - each of us is going to bring his or her expectations, experience, needs, wants, and ideas to bear. 25 years of studio experience has led me to prefer more powerful amps and what they do. YMMV.
Then again, my DG30 is a very loud amp that can be set up with a lot of headroom, and the same can be said of an AC30. So...whatever works for someone is good.