My first guitar amp was my brothers old 50 watt marshall, master volume 2x12 combo. These were great amps and when I eventuall joined a band on guitar just over 20 years ago, I bought the head version and ran it into an old marxhall 4x12 with green backs in it. This servered me well till I went to a Superbass Head with a Marshall Powerbreak.
At the time I was palying with Martin Kidd (Cornford/Victory designer) and we're good friends. He made me a 50 watt head, with dual masters volumes and a gain boost section, which meant no O/D pedal needed. FX loop. It was awesome and so I set up a company and sold a few.
http://www.wkz-amps.com
There's a great sound clip on the website, demoing what you can do with it. A simple amp with a great core sound. The lengendary Producer, The late great Chris Tsangarides played one live with his band ExMoore and recorded almost everyone that came into his studio with it.
They haven't been available to buy for many years now as I have moved on but I still play live with Martin a few times a year.
I still have a White half stack, a 50 watt combo and the prototype 18 watt combo. All working perfectly but not being gigged anymore as thy are too heavy for my aging body.
There are plenty of good valve amps out there. I also have a modified Vox AC30 CCX. I have changed some resistors in it, as found on a website somewhere, to make it sound better. It worked, it's a lovely sounding thing, with blue speakers. I keep it in my office, at work, for the times I need to learn something. Again a touch too heavy to gig with now