I use to have over 80 safety razors with most of them being Gillette ones like the adjustable in the photo. Just go antiquing and find a good one. As a collector back then I’d find so many that if I already had one in my collection, I’d restore the other one and sell it for a little profit. Personally I found single edge razors to be better for me(injector razors to be exact) so I sold all of the double edge ones for single edge’s. I highly recommend finding an old Schick injector(type L is super common/found cheaply and happens to be a favorite of mine because it’s soooo smooth) or buying a Supply SE razor which is a modern injector razor.

Double edge razors have thinner and cheaper blades, but the injector blades last me longer and with them being stiffer they are easier on my neck. They’re also have the shaving angle built in, with double edge you have to find the right angle, so it’s easier starting out IMHO.