I post this every time it comes up: I am convinced that Snow Leopard is remembered overly-fondly because Lion was so comparatively bad. I did a lot of testing between Snow Leopard, Mountain Lion, and Mavericks in Virtual Machines side-by-side (because I wanted to switch my main machine over to one of the three), and could not find any reason to pick Snow Leopard. Mavericks really benefits a lot from memory compression in particular (although this is of course moot if you have memory to spare).

I admittedly didn't test with an HDD though, Snow Leopard would probably have done better there. On the other hand, you give up a lot of good, useful features by going with Snow Leopard. I know a lot of Mac users were annoyed with autosaving when it was first introduced, but I remember typing essays with Pages on Snow Leopard in High School, and losing many hours of work due to the lack of any autosave functionality.