Short answer: from those 3, definitely Kensington. Long answer:
I owned Kenstington SE years ago but I’m still a big fan. Wonderfully musical, good detail, a beautifully balanced speaker. I think the GR series should make it more detailed without messing up its mojo (I also had Canterbury SE and upgraded from them to GR - a BIG improvement there).
The DC10A, when I auditioned them at my dealer, always practically ran me out of the room. Detailed - sure! But also bright and lean - I vastly preferred the Kensington. Maybe gear matching could help to some degree. I wonder if that Alnico/pepperpot driver has a different kind of sound when you use it with bass reflex porting (like 10A, Yorkminster SE, GRF), that is less lush and musical than the vented enclosures (Kensington, Canterbury). I haven’t heard GRF but on paper (if not in looks) they’re similar to the Yorkminster SE from the prior line - and the "magic midrange" wasn’t quite there for me on the latter. It seems like I’ve seen 50% (or more) discounted floor model 10A’s come up for sale periodically, for years now. Every time I always think to myself "I’ll bet they’re deep discounted because they can’t sell them off the floor". Such a beautiful speaker too. If they sounded like Kensington I bet they’d have flown out of showrooms.
Legacy series - haven’t heard them, but they look very cool. Tulip waveguide DC implementations can indeed sound very good, and work better with bass reflex cabinets than I’ve heard so far from the alnico/pepperpot drivers.
I’ve been trying to keep up on owner impressions of Fyne from former Tannoy users. So far I get the impression of a more detailed, modern sound. Hopefully not too much like the 10A haha. But people seem to really like them! I also want to like them, because it seems to have the core Tannoy team from before the Behringer takeover, they’re built in the UK, and obviously they’re dedicated to the dual-concentric approach. Hope my dealer picks them up.
I’ve heard Sopra 3s a few times at my dealer and I like them a lot, but still prefer Tannoys. You won’t be missing detail in a transition from Kanta to any of these models. Can’t speak for the Rockports. I remember Harbeths (long ago) being nice at lower volumes but there is no way I could rock out to them like Tannoys. I wouldn’t know they were supposed to have the same "British" sound unless you told me! Many of us hear our first Tannoy DC and then it’s "game over". Happened to me with Eyris DC3’s in the 2000s. You’ll look sideways at all physically separated tweeter/midrange arrangements from here on out.
Also (sad news time), word is that Tannoy’s Scotland factory is permanently closed and nobody seems to know for sure where future Prestige/Legacy products will be made, or even if they will. Who knows if stock dealers have on hand is the last of the Scotland builds, or if they’ve already switched to China/etc. If you trust your dealer, ask them what the word is! But even most dealers have a very very hard time getting decent communication from Tannoy - and practice this goes back for years, not just current Behringer ownership.
