Edit to further elaborate I've heard that solid state amps are used in metal more commonly because they have a different tone then tube amps which would be more common in a bluesy type sound.
Poets around the world throughout history have tried to quantify beauty and failed. I always find it humorous that guitar players think they can succeed when they are far less well-equipped to the task.
However, a couple of points:
1) Old solid-state amps were mostly built to be cheap, so they sucked. Modern ones are constructed significantly better.
2) Vintage tube amps often have more variation (and may or may not have been repaired faithfully which increases the variation) so you occasionally get one that has "magic".
The downside is that most of the amps don't have that magic--you will probably never encounter the "stage queen" personally. Another downside is that you can lose the "magic" pretty easily.
This is something that the vintage amp guys all gloss over. If you got the "stage queen"--congratulations! Of course the other 300 in the production batch don't sound anywhere near as nice.
3) Dimebag Darrell, for example, liked his solid-state Randall sound very much. Who are you to argue?
4) Modern modeling amps are getting REALLY good at mimicking the tube amps. This means that you CAN have that "stage queen" that you will never encounter personally. And you can create sounds that the stage queen can't. Whether they're "pleasing" is a different story.
5) Each individual amp has a "sound"--whether solid-state or tube. The question at the end of the day is: "Do you, personally, like how that amp sounds?" And, if the answer is "Yes", plug your guitar into the amp, play what you want, and tell the poseurs to go pound sand.
Dimebag was paid to play Randalls. When the deal expired, he swtiched to tubes.
Those Randall JFET amps sound like "chainsaws" when they break up, and I'm pretty sure he liked that. And he used them from way back when he wasn't famous.
The KRANK stuff came MUCH later in his career and KRANK paid him quite a lot. And there's lots of discussion about how he didn't really like the KRANK stuff all that much.
Having said that, for the average bedroom/small gig player these subtle differences are too minor to bother with. Especially when a modeling amp can accurately emulate so many different valve amps. Sounds good and you can save a lot of money!
BUT - I would be remiss to say that you shouldn't own at least one valve amp. Take the one you emulate the most and buy it. You'll be happy!
They've gotten quite good, they're about 90-95% of the way there... but that 5% is pretty stark if you know what it is.
That said, convivence, portability, reliability, etc...
Partially false. The general trend in metal has gravitated towards tube amp distortion (and digital modeling of it) precisely because of the different tone and responses vs solid state amps.
As a guitarist there's a certain response you get with a tube amp vs digital and solid state.
As an HN reader, I struggle to describe and quantify this quality besides the generic descriptors of 'response' and 'feel'.
One thing that can make even modern solid state amps sound bad is crappy speakers. The bulk of solid state guitar amplifiers are combo amps with a single crappy 10” or 12” inch speaker in a cheap cabinet.