My knowledge and experience is this (I may have a couple technical details incorrect on the modeling front, feel free to correct me, but this is my current understanding and experience):
Tube
Because of how tubes work, they have a natural compression as you reach the limit of their operating characteristics. This happens even when still clean and just approaching the grit and distortion levels. As a result, they have a touch sensitivity that makes it so that, when gain set to the near edge of break up, you can go from sparkle clean to afterburner of a jet distortion by simply laying into the strings slightly with your hand. You don't have a need for different channels when you can get that range out of the single channel signal without even touching a knob.
Solid State (analog)
Clean and clear with headroom. The earliest solid state amps will distort, but makes an ugly raspy kind of distortion when you hit the operating limits of mounted circuits, ICs and transistors etc. Solid state amp companies have done a lot of work over the years to work around this by emulating compression and internal equalization that emulates tube response. They also have resorted to making separate channels for clean, overdrive and distortion to more fully emulate the range of tube amps, but requiring physically selecting separate channels for those sounds. But they can sound very good and work for many applications.
Emulations / simulation / modeling / convolution (including Solid State amplification of digital processing)
One of the first devices I would consider an emulation/simulation was the Scholz Rockman, which was a solid state circuit designed and patented to emulate a Marshall stack as recorded in a studio. It used diodes to simulate tube distortion with compression to simulate the touch-sensitivity of a tube amp and studio compression in mixing, and it had the earliest circuit-based speaker emulation built into the circuit, though being a headphone amp, it would require a clean solid state power amp to use it like a regular guitar amp.
The SansAmp PSA-1 was a pretty successful emulation of various amps using circuit board technology. IME my PSA-1 requires an outboard compressor to give it the touch sensitivity of a tube amp, but the sound itself can be made to be pretty dead on, if you A/B it next to the real amps and know which knobs to twist. Same thing here, it requires a clean power amp to use it like a regular guitar amp.
Modeling takes different forms and varies in success.
- Line6 had a Vetta/Flextone series of amps that had really good emulations/models of amps - I believe they were among the earliest to use software emulation? with a solid state power amp. The models were excellent, however they did sound like a recording of a good amp, rather than like standing in front of a good amp.
- There are also methods of software emulation. One is modeling all the components of the system and building the circuit virtually, another is profiling a device, something akin to but more complex than convolution, and running the incoming sound through the profile to color and shape the sound to match what it would sound like coming out of the actual amp. The best example I've ever played was a Kemper. It sounded and felt like using the real amp. Any clean linear solid state amp will do into a full-range speaker cabinet as all the tone is in the Kemper profile.
When Solid State is the power amplification for a digital model or emulation, the fact that it's solid state is irrelevant. It's the best choice because it's clean and linear and will reproduce the model perfectly without coloring the sound or compromising the sound. Also is better using a full-range speaker cabinet, as the modeler takes care of making it sound like a real amp.
These days, with things like the BOSS Katana, VOX Valvestate, Fender Mustang amps, there are great options for digitial/software amp models that are very good and have a clean solid state amp built-in. The days of raspy solid state distortion are gone, unless you really want to use that sound. Line6 also had an amp for a while (Spider Valve) that had it's modeling up front and a Bogner-designed power amp section to really play and feel and sound like a great amp.
As far as "pop blues rock jazz country", the 'four?' types of music, I've played all of those with all of the above. The decision of which gets down to:
- Am I recording? - tube amp
- Am I playing at home and can crank it to my satisfaction? - tube amp
- Am I playing at home and have to be careful of neighbors? - software emulation through solid state turned down, Katana, Mustang, SansAmp, or Rockman
- Am I gigging?
- Playing a small place, have to use stage sound? - Katana, Valvestate, Mustang, etc.
- Playing a small-medium size place, running quiet stage? - SansAmp (which is also a DI) to the board; or even pedal emulation > D.I.
- Playing a large place, can use stage backline? - Marshal, Orange, Fender behind me
As far as amp type (whether model or real), the decision for me is:
- Pop - VOX
- Blues - Fender Tweed or Blackface
- Rock - Marshall, Hiwatt, Orange
- Jazz - Roland JC, Fender Blackface
- Country - Fender Silverface
