Don’t forget Pentax
Great range of old lenses to choose from,decent entry level camera in the K-m, nice mid range with the K20D and the new K7 which looks a match for Canikon models in that price range
My favourite is the recently discontinued K200D, in built anti shake,dust cleaner and best of all weather sealed.
Be careful with the cheaper Nikon’s, they don’t have a AF motor, so you will need lenses with a motor built in and they ain’t cheap. Same with Image stabilistation, if the body doesn’t have it, you will have to buy lenses with it in
Olympus and Sony both make good cameras too, don’t be lulled into thinking you must buy a Canikon.