I have a lot of nice M42 glass and a nice Spotmatic, and a nice SV, but for me a Contax/Yashica body plus an M42 adapter is the best body for M42 lenses (though I don't have a Bessamatic which would be the only thing which might be better, maybe, but it will cost a lot more). Brighter viewfinders, much higher available shutter speeds, auto exposure modes, easier metering experience (even considering the stop down). It is a much better solution than it might sound on paper. Just try it to be convinced. Something like a Contax 139Q is dirt cheap, and as small as an SV if not smaller. Plus you can use Contax lenses on them too.
If this isn't obvious, and it might not be, just try it and you will likely be quickly convinced. I know there is something nice and "pure" about a Spotmatic, but a nice C/Y body is just easier to take epictures with. FWIW, I have owned M42 bodies from pretty much every other M42 brand as well.