Yeah, with my 5DII I usually don’t go above 2500 ISO either. the 5DIII has a much more responsive AF system and all the points are cross-type so I don’t have to worry about that.
I’ve been handed an entry-level Nikon before (my aunt’s, she’s only an enthusiast but shoots on auto) and I could not for the life of me figure out how to change the aperture, lol! Maybe a higher-end model would be easier to find those controls. However I’m sure that would take me a few hours to actually get comfortable with a Nikon since I never actually shot with one.