I bought and sold an EOS M + 22 + 18-55 + adapter. Then when the second fire sale (at $250) came around, I snagged the M + 22 again and added the adapter as well. When I had it previously, about the only lens I mounted on it was the 40mm. However, this time around I have additional lenses and find 2 that work really well with it. I use the EF 35mm f/2 IS USM and the EF 50mm f/1.4 USM both work wonderfully on it. The EF 85mm f/1.8 also works well but due to the longer focal length I find it slightly more difficult to compose images and locate my subjects - it's not terrible, but it's not great either.
For me, the 22 + 35 IS + 50 is a GREAT, LIGHTWEIGHT, small(ish) walkaround combo. Personally, I find zoom lenses on the M to be cumbersome and I don't really like them. Both the native 18-55 and adapted zooms. Adapted zooms are worse. Probably a personal preference. And note I haven't tried the 11-22 or the 55-200.
I agree, a fast 50 on the M will complement the 22 nicely. Much like a 35-85 combo on FF.
I didn't really like the 50/1.4 though (bought and sold it 3 times), so I am thinking on the FD 50mm lines.
If that is the case go for a M42 mount 50mm. I could not tell any real optical difference between the FD 50mm 1.8 and the EF 50 1.8. I expect the FD 50mm 1.4 would be the same. I have thought about tracking down a FD 55mm f1.2 that may be worth it.