I like valves and solid state. Like most things, there can be good and not so good interpretations of each type of design. I have Class A valve and Class A transistor power amps that sound equally good (but different), I also have Tripath type amps that sound very good.

One Class AB power amplifier that is cheap to buy second hand (and new) and really sounds ridiculously good is the tiny Parasound Zamp V.3. If I have more knowledgeable friends visiting, I sometimes have this little amp running and they think I'm still using my valves until I tell them.

I also had a Denon PMA-350 SE integrated amp for a short while a few years ago and that was a powerful and very good sounding unit, so much better than I had expected it to be. Way superior to the PMA-250 SE that was all the rage in cheaper integrateds back then.