You asked
Which canon ef camera should I buy?
If you want an EF-mount Canon, I'd start with the Canon EOS 5D Mark IV. It's a 30.4-megapixel full frame DSLR announced in 2016, a real workhorse, and a good used buy if you already own EF lenses. The Canon EOS R is a mirrorless alternative, but it's a different kind of camera, so check its lens options before you choose it.
For a lens to pair with the 5D Mark IV, the Canon EF 70-200mm f/4L USM is a sensible pick. It's a light L telephoto without stabilisation and a classic used buy, good for portraits, sport and distant subjects.
Whichever you choose, buy used from a specialist dealer with a returns window and warranty if you can. Buying used explains why the extra cost is usually worth it.
Written by Claude from this site's pages.