Sometimes I shoot macro, although I do not have a dedicated macro lens as yet.
This caught my eye.
Canon makes a 50mm f/2.5 "macro" lens that might work very well for you. It's not a "true" macro in that it won't get you to "life size" (1:1) without the adapter, which *can* be somewhat pricey to buy from places like KEH.com. The lens itself is a bit noisy while focusing, and that can tend to scare jumpy little critters like bugs. But it can produce some very nice, sharp images and, to my mind, it "feels" a lot more solid than the nifty-fifty. Also, the mount is metal instead of plastic, so no worries about the lens getting stuck to the camera. I'd recommend you look into this lens.
I know you said you'd prefer something with an aperture ring. The thing is, I'm not sure Canon even makes such a lens anymore since they dumped the FD/nFD system and went to fully automatic with the EOS. As far as adapting older lenses, my advice would be to forget about old Canon lenses and stick to other lenses such as M42 screw mount. FD/nFD lenses will require that adapters have glass inserts in them to achieve infinity focus which will degrade your images. 
KMC
