Depends on what you mean by "using most." Do you mean taking the most number of photos with? Or do you mean taking out to take photos most often or most days?
If you mean taking the most number of photos with, my digital Nikon D750, which I have taken thousands of photos with. This compares with maybe a couple hundred with my film cameras. I basically use the D750 whenever I may want to share the pictures with people outside of my immediate family.
If you mean taking out most often or most days, probably been using my film cameras more often. Mostly Nikon F6, although I try to give all of my film cameras -- including Nikon FM3a, Nikon FE2, Olympus OM-4Ti, Om-2n, OM-1n, etc. -- a fair workout. Also have shot several 120 rolls with several Mamiya 6 bodies, and also have shot a couple of 35mm rolls with my Olympus 35 SP bodies.
Also have been taking a few digital photos with my wife's largely unused Canon T3i -- bought an OM-EOS adapter and have been trying out my OM Zuikos on digital. Results have been OK, but not that consistent, due to difficulty in focusing precisely using viewfinder. Live-view photos with enlargement have been much more consistently focused precisely, but the process is rather cumbersome. Also, I have noticed that the Canon T3i photos have alot more chroma noise in lower light than the more modern Nikon D750 shots.
Tried the OM Zuikos on the Nikon D750 with an adapter (with glass elements). Photos shot wide open or close to wide open have a bit of a soft focus effect, while stopped down are somewhat better.
Still tempted to get a modern mirrorless body (with focus peaking) to use the OM Zuikos.