My largest that I have in my possession is an 18" Obsession, I also have 14" and 10" scopes.
As a 3RF Australia Volunteer I also have access to 20", 25" and 30" scopes. But to be honest my preference is for people younger and larger than me to transport and set those up, as they are physically quite demanding and every year they just keep getting heavier
Have a 20 inch Obsession in a two story roll off roof observatory.
Mark Suchting Mirror F5.0
Made the Scope from David Kriege's Book.
Aluminium Bearings from him.
On equatorial platform.Electronics Tom Ozypowski.
Love it!!!!!!!!