All of the Zu speakers I heard were extremely dynamic an d lively sounding, but, they were also bright, harsh and one gets tired when listening in sessions longer than a few minutes. This is really a matter of taste, so one must hear the speaker. I like lively sounding speakers, which is why I like some horn systems (I own a horn-based system) and some other high efficiency speakers, but the Zu is too far out for my taste.
I don't think that the Tannoys I heard were extremely smooth and laid back. The Westminster and Turnbury models I heard were fairly lively sounding and "smooth" was not a term I would apply to the sound--there was a touch of a peak that made the sound slightly sibilant in the top end of the midrange--this issue notwithstanding, I liked the Tannoy speakers I heard. If you are looking for something similar, but, to me, a little better sounding, audition Fyne speakers. This is a company founded by Tannoy engineers who decided to make their own speakers. The F1 model is particularly good sounding.