Tube amps - what 3 things…

what speakers?

different tube amp qualities and features matter if you are driving hyper efficient altec horns or audio notes, less efficient harbeth monitors, reactive focals or revels, or resisitive magnepans

just like ss amps, they should be optimized to the speaker load and power/current demands

right?

What speakers. A VERY important consideration. Auto bias, tube rolling ability, quiet design

Quality transformers are a key part. That's why I like Quicksilver.

https://www.bandwidthaudio.com/post/output-transformers-the-heart-of-a-tube-amp

You didn’t mention Tube Preamp, which I think is more important regarding features and system sound

1. my Cayin A88T Integrated Amp, Bias Controls

I wish it had exterior bias meter and controls. Someone else mentioned auto-bias, that would be even nicer. Unfortunately I need version 1 as it is the only one with 16 ohm taps, and it’s bias adjusters are inside, take bottom off, better avoid touching ...... Great review made me pick it, but I wasn’t paying attention to bias controls.

Preamp Features: My McIntosh mx110z is a full featured Tube Tuner/Preamp, up to spec by Audio Classics, especially new gold rca jacks. I started with Receivers, then separates, then no controls, now back to full features, integral phono and tape .... Vintage McIntosh units have their MODE switch, which is very helpful for me to match my speakers side to side when messing with level controls, stereo reverse, l to, r to mono .... Not everyone needs the Mode control, but I do.

2. IF I went for an Integrated Amp, with remote features, I would definitely want at least remote balance as well as remote volume. My Cayin is an integrated amp, but I only went for that to get remote volume so I could stick with my Vintage Preamp. I only use 1 input, and I think remote control inputs is dumb.

There are many errant tracks that benefit a LOT from a small tweak of balance, especially compilation cds/lps/tapes. A lot of recorded live performances, the 1st track, eh, not quite right, the room with people in it is different than the pre-concert set-up. the engineer figures it out, makes slight corrections for the rest of the recording,

3. IF I didn’t have level controls on my speakers, then I would like to have enough tone controls (not a full equalizer, but several bands, not just treble/bass).

That’s hard to find on modern equipment. I just don’t believe in buying a great speaker and expecting it to sound great in .... unknown room. Much room treatment results from the lack of level controls/decent tone controls that can be refined using a sound pressure meter (quite affordable these days).

My advice is to download the Decibel X-pro audio app for your smartphone So you can get a rough idea of how loud you like to listen. This will make a big difference. I used to think that high power was required then I got speakers that were 93dB efficient And started listening to 7 and a 1/2 W. And I loved the sound then I went down to one and a 1/2 W and love it even more. But I’m listening right around 70 to 75DB and fairly close to my speakers. This wouldn’t work for a lot of people.

 By the way, I think you're getting a lot of good advice on this thread actually. Ultimately you gotta think of things in terms of a system. And the speakers in the room and the amount of stuff you have in the room is part of that system. Donnie Darko (?) has a good YouTube video about room treatment that's worth checking out.