Need help: Tannoy or B&W?

Um, what??

I wouldn't buy either unless you had heard them.  I mean, I have a strong preference, but because they sound so dissimilar. I'd say if you can't hear either skip them and stick to things you can listen to.

The Stirling III LZ looks great on paper, but has had mixed reviews - and it's hard to tell if that's just sour grapes from the distribution drama Tannoy went though recently, or something inherent in that model, OR just a bad sample that got sent out. Its 10" pepperpot driver SHOULD be capable of sounding great. 

I'm a die-hard lifelong Tannoy fan and own some 7 pairs now, including 2 sets of Canterbury (SE and GR). So I'm clearly biased towards that - the dual concentric sounds more natural and like music to me than multiple drivers all spread around. 

It's been a while since I heard B&W but it was first an older 802 Nautilus model that sounded very unnatural to me. No way! And then a Signature Diamond floorstander which I actually quite liked a lot - but nothing so much as to sway me from Tannoy :)

If you're looking at used B&W, maybe consider used Canterbury. Great model. The SE version is darker and thicker, and needs to be paired with gear accordingly (and probably supertweeters). The GR is extremely well voiced out of the box (no supertweeter needed). 

What’s your system ,having sold Audio for decades 

room size, cables, Amp,preamp front end need to know B&W like current 

not so much with Tannoy Totally different character type of speaker I sold both while in the U.K , B&W more dynamic detailed ,Tannoy a bit more laid back forgiving  that is why what you are looking for is so vastly different in the 2 Loudspeakers  the older B&W is for sure more detailed pronounced ,it could be tough if not tailored  by equipment or cable factors  and room treatments .That is a tough one  .

Neither - without knowing the rest of the system.

I’ve had both and both are excellent speakers. IMO you can beat Tannoys for soundstage and imaging. In my main system I’ve settled with Tannoy Churchill’s with super tweeters. I can literally walk around the room and get great stereo imaging. They are smooth, very efficient with beautiful midrange and visceral in the bass range when called for. They are the only speakers I know of that can be both intimate and thunderous. I can’t recommend them enough.