The 308 is fine for coyotes. So is the 260 and 6.5x55.
I love the 6.5x55 for coyotes, but that's just my personal preference as well as a rifle that shoots minute of coyote out past 400m. As long as I do my part that is.
Coyotes don't care what you kill them with. Settle for the rifle that you can shoot well and can handle the recoil on for lots of repetitive practice shots. Lots of practice under different conditions and ranges is the real secret to successful coyote shooting.
The only other caveat to calibre is which bullets are available for the conditions you're going to encounter. There are plenty available in all calibres between 17 to 30.
Purpose built rifles are also another factor, but that's a whole different ball game.
bearhunter