Head to head
Canon New FD 28mm f/2.8 vs Minolta MC Rokkor 28mm f/2.8
Both are normal-bodied moderate wide-angles from the big two SLR systems, same focal length, same f/2.8 aperture, and both turn up cheap in the same bargain bins, so people cross-shop them constantly. The biggest practical split is the mount: the Canon is FD breech-lock built for Canon film bodies, the Minolta is SR (MC) for Minolta film bodies. That mostly decides things before optics ever enter the picture, because adapting either cleanly to a modern mirrorless body is its own conversation.
How they differ
On a film body you are locked to the matching system, and that is usually the deciding factor. If you already shoot an AE-1, A-1, or any FD camera, the Canon drops on and meters; if you have an SRT, XD, or X-700, the Rokkor is your lens. The Canon New FD generation uses the later bayonet-style breech lock that mounts faster than the old screw-collar FD, while the MC Rokkor is older full-manual Minolta glass with the meter-coupling tab. Both have nicely damped focus throws and real aperture rings, the kind of feel modern lenses skipped. Stopped down to f/8 either one is a sharp, useful 28 with the contrast film flatters. Wide open at f/2.8 you are buying these for the look and the price, not for cutting-edge resolution. Flare control favors keeping a hood on both, and good copies of each are common enough that condition matters more than name.
Choose Canon New FD 28mm f/2.8
Get the Canon New FD 28mm f/2.8 if you are already in the FD system or plan to be. It pairs naturally with the common, affordable Canon film bodies, the New FD mount is quick to swap, and copies are everywhere, so you can be picky about condition and price. A sensible everyday wide for FD shooters who want one clean 28 and done.
Full Canon New FD 28mm f/2.8 guide →Choose Minolta MC Rokkor 28mm f/2.8
Reach for the Minolta MC Rokkor 28mm f/2.8 if you shoot Minolta SR bodies, or if you adapt vintage glass to mirrorless and prefer the older Rokkor rendering and metal-barrel build. Minolta's coatings have a real following, and these still sell for little. The right call when your camera is an SRT or X-series, or when you simply like the way old Rokkors draw.
Full Minolta MC Rokkor 28mm f/2.8 guide →The verdict
Honestly close. Same focal length, same speed, both good cheap 28s, so let your camera mount pick for you. If you are starting fresh and adapting to mirrorless, choose on price and condition of the actual copy in front of you, not the badge.