Kunin, IMO, is unlikely to be a NHL C. Right now, Coyle is clearly better than Ek, but Ek is very young. The hope is that Ek has a higher ceiling at C. Coyle can be a decent C. He's a funny player that can really tease you because he looks like a dominant player for stretches of time in a power forward way, then goes back to sleep, offensively, anyway. The good news is that his floor is reasonably high...he's a responsible two way player.
Ek is likely to be a terrific defensive C at a minimum. He doesn't flash any elite offensive vision or puckhandling. Nice shot, though, and he is a good skater.