Best Mesh WiFi System

I use Google Mesh, no complaints and easy to set up.  

Netgear Orbi Mesh - although just like other routers, instead of a clear "best" there are probably several brands/models that would meet your needs.  As in the past, what works well now may eventually need replaced as technology develops further.

The Orbi system works great for me. Although my main server is hardwired, my garage/outdoor system is connected directly to one of the mesh satellites by a very short CAT8 cable and it works perfectly plus gives me enough range to control the server from my iPad while on the porch or the patio. 

So far 4 different systems.
Best value?
Depends on how good a shopper you are.
Best coverage?
Good luck finding anyone here that has compared.
Best form form factor?
Only you know what you like.
All you know for sure is that everyone is happy.
Go for it.

I've had the Google wifi since it came out and it works wonderfully though my home and back yard.  This has since been superseded by Nest Wifi which adds better range but no ethernet port on the nodes. 
I have 40+ devices (including music streamers, nest cams, TVs, etc.) connected at any given point in time and it works great.