Gillette Slims are easily found in good shape and are an excellent razor. Fatboys are probably better (and what I really prefer) but more expensive.
Gillette got it right with those two, no need to do something weird or exotic to get a really good shave. The later Black Beauty/Super Adjustables are OK, but I don't like the skinny handle and the long version (which is the most common) gets in my way shaving. More expensive too, since they didn't sell anywhere near as well as the Slim -- disposables rapidly wiped out the double edge razor market because they are cheaper up front (although not in the long term). They shave just about exactly the same as a Slim.
+1! ‘Gillette got it right with those two..’ At least for me!!