Not that I don't like my .204 yodeldog3, BUT the 22-250 and the .220 swift among many other calibers will kill a coyote as well or better than the .204. Using the word "best"when comparing calibers is risky business. It takes more than speed to be the best. Accuracy, IMO, is more important, and the ability of the shooter to shoot accuartely rates right up the scale as well. A good bullet is important too.
Besides, if you're using the little 32 gr. ballistic tip bullets in your .204 to reach "4250 fps", than you are setting yourself up for dissapointing results with the .204.
Dan has on occasion killed coyotes with a .22 lr, so I'm quite sure he knows what it takes to kill a coyote, and I'm tellin' ya, it takes more than a speedy bullet.