QUAD vs Martin Logan vs Magnepan

You have to decide what kind of sound staging you want before you choose one of these speakers over the other, especially the Quad vs any panel. The are very different!
If you want a high resolution point source speaker other than a more conventional cone design, Quad is your only choice (at least that I have listened to).

FWIW, and its probably not much (!) I have listened to Maggies and ML's and while both can be impressive neither are point sources which is my personal sonic preference. Of those two I found the Maggies to have a somewhat warmer tone than the ML's but I prefer the sound of the electrostat panel in the ML to the Ribbon in the Maggie. Conversely the Maggies bass is more of one piece with the rest of the speaker than the box sub on most ML's. In fact some of the best bass I have ever heard was from Magnepan panels. As I said, FWIW.

Hands down, the Quad is the best that you seek!

Goood Luck!*>)

I have owned Magnepan 3.6's and now listen to ML CLS's with a ML Depth sub. The 3.6's needed to be playing fairly loud to sound their best. The ribbon tweeter always seemed to be a bit hot. I could never quite get it right. I even actively biamped the 3.6's. The CLS is a low level detail champion. I don't have to crank up the volume to enjoy them. They are totally seamless since they have no crossover and are basically a single segmented driver. I run the CLS full range and flush the sub in from the bottom up. The 3.6 had much better bass and in my opinion does not need a sub. If my listening room was larger, the 3.6's may have been the ticket. The CLS seems to work better for me.

stick with the maggies, even if you upgrade. the quads are good too, but you will spend more for less.

You get what you pay for!
MMG's are cheap and may sound really good in the "right" position with the "right" amp in a really narrow sweet spot. Bigger Maggies are a much better comparison to ML & Quad.
The ML's are more forgiving of listening position and easier on your amp. My favorites for the money.
If money doesn't matter, I'd pick the Quads.
Keep in mind that power matters with these speakers more than most. I wouldn't even dream of running these with less than 100 watts and would prefer 200+.
My final rant: Room size matters. These all like big rooms. What are your room dimensions? Ceiling height? Can you place the speakers 3 feet from any wall? I heard the quads in an amazing room but they were 5 feet from any wall, in a room about 20 x 35 with 11 foot ceilings and ran on huge parasound monoblocks.