Lots of different Tannoys. Canadian-built conventional speakers (C series). Vintage speakers with woofers and separate compression tweeters. Dual-concentric speakers of all sizes and vintages - System series, 6 series, DCM series, older classic dual-concentric Tannoys with names like Westminster, Belvedere, Churchill and drivers names like gold, red, silver in sizes of 10-15 in. There are also studio monitors and constructor dual-concentrics that are used in studios and churches or gyms, respectively.
I think the System series Tannoys sound very good, with excellent power handling and great imaging. The Studio Monitors are equally as good. Some Tannoy aficionados prefer the sound of the smaller classic Tannoys of 10-12 in. over the 15 in. versions, apparently for overall cohesiveness of sound. Many people who own the older Tannoys add super tweeters to add a bit more high frequency reach and "air".
The older Tannoys are limited in terms of power handling, although they play plenty loud with little power. Many of the later models such as the Studio Monitors are still fairly efficient, but will handle much more power than their ancestors.
Quite frankly, I've yet to hear a Tannoy I hated. Many sound wonderful, at least to my ears. The strength of the dual concentric sound is the cohesiveness of the sound. The driver alignment is the key. The sense of scale with some of the larger, older Tannoys is amazing. They still make the Churchill and Westminster. Regarding the Westminster. Each speaker is the size of a fridge and costs a bundle. I've heard my friend's pair. If you can afford them and have the room, they are definitely worth a listen. , especially if they're accompanied by a $3000 pair of Tannoy's ultra-sonic tweeters.