M's are great and M2's the greatest - but for somethings a SLR works better!
My stash of these are - at the moment. 6 Nikon F's that have various lenses attached to them. Usually used for Macro work.
55f3.5 Micro Nikkor, 105f4 Micro Nikkor, 200f4 Micro Nikkor and the bellows kit with a 135f4 Nikkor Bellows lens. I like the F's as they are simple, rugged and I can use my Nikon Rf cassettes in them.
I also have an old 28f3.5 F lens (chrome barrel), the 55f1.2 (not the Noct though) and a couple of 105f2.5's and a 200f4. Also the 58f1.4 Nokton and the 40f2 Ultron with the small Proxar lens for close-ups.
A Leicaflex SL Mot, black paint - though it is a bit brassy too. 60mm f2.8 Macro Elmarit and 180f3.4 Apo-Telyt.
Bessaflex (Cosina re-make of a Pentax Spotmatic - with a better meter). That one is used for adapting to a microscope or with a Takumar 50mm f4 macro.
Konica Auto-Reflex (full frame/1/2 frame capability) and the Konica 50f1.8 - though most of the time it is used with an adapter that allows me to put Nikon SLR lenses on it. Great for close-up and Macro too.
Only one F2 - strange looking as someone painted it hammertone gray. Good for long exposures as anything above 1/4 sec is non functioning. B and 1 sec works fine though.
There are also two ultra wides for the F's, a 12f5.6 Heliar and a 15f4.5 Heliar and, if I removed it from the S2 - I could put the 21f4 Nikkor on one too,
Two of the F's are designated parts cameras. They still work, but if I ever need parts for my S3's or SP's - they will be raided.
I used to shoot a lot with SLR' Nikon's for work. Mainly F2's and F3's. Great motordrives, good finders and the modular construction allows you to "build" the camera to a specific purpose. The 6x sportsfinder, heavy, but great for macro work. The prism finder as a walk-about body. The Photomic's that I have (2) are dead - so they only clutter up space - but in case one of the prisms in the regular finder dies - I can salvage one from a Photomic.
The good thing with the Nikon F's is that they are generally cheap and as they are mechanical, you can still get them fixed. In many ways, it is one of the best designs for a SLR ever.
The F2 was a slight improvement and the F3 was a great "work" camera - with the MD-4 motor on it.
Oh, then we have the two "pool" lenses. Terry, Chris and I have a 560f5.6 and a 400f5,6 set up with a televit focussing grip. I think I got that for about $400 some years ago. If I ever need a long reach - I can get those. Looks a bit like some kind of grenade launcher though!
SL2's are good, but I can get several F's for what one of those costs and the SL-Mot takes care of the few rolls I shoot with the 60f2.8 and the 180f3.4.