You pick

Another long time Quad ESL owner--since 1973. I recently had my pair restored and use them with a pair of restored Quad II amps with GEC Kt 66s. They sound wonderful-- I hadn't run them in a long time; I had changed to the Crosby modded Quad 63 back in 1990 or so, for many of the same reasons cited by @willemj 
I always thought that upgrade was a bit of a trade-off-- a more useable speaker, with fewer limitations, but the original had a greater midrange coherence. 
I use these as part of a second system. (My main system is horn/SET-based).
Re Martin Logan, I haven't heard the latest crop- I remember hearing the very large one-- Monolith? in Paris in the late '80s or early '90s. The original CLS? was very well regarded though it was ruthlessly revealing.
Can you listen to both, properly set up with associated components before you make a decision? 
FWIW, I think my refurb'd 57 panels sound better with the little Quad tube amp than they did back in the day, when I ran them with a then current production Audio Research tube amp (Dual 75a). The ARC may have been the more useable amp, overall, but there is a synergy with the Quad amps- small and dated as they are, they work magic with the original Quad loudspeaker. 
Last thought- verify who did the refurb, how old it is, and whether there is a good protection circuit installed. Those speakers are easily damaged by arc'ing. 

I have owned Quad ELS75’s since the mid seventies, but replaced them a few years ago with the modern 2805. I had two reasons. The first was that their life expectancy is finite, and they had already survived longer than could be expected. The second was esthetic: the 2805 really fits a lot better in our modern interior.
Sonically it was an improvement as well, even if the ELS57 is still a very good speaker, and even if the difference was not dramatic. The 2805 can handle more power, has much better bass, and disappears in space like no other speaker. The downside was that it is less efficient, which I cured by replacing the refurbished Quad 303 power amp with a refurbished Quad 606-2. In the end I decided I wanted even more low bass extension in our new and much larger living room, and I succesfully added a subwoofer (B&W PV1d with Antimode 8033 room eq.).
ELS57’s are very amp unfriendly by the way. The Quad 303 was more or less designed for them, but other amplifiers vary (i.e. have been known to self destruct or destroy the speaker).

Quads! I have been a happy owner since 1981! Presently own two pairs! Have used mine with a Bedini 25/25 and Futterman H3AA's.