I've used a bunch over the years
My favorite all around 6mm coyote bullet is probably the 70gr Ballistic tip. It has enough weight to break one down that is running away and it usually doesn't exit on a broadside shot. It might not kill them instantly when they are running away offering only a hind end shot, but it will disable them so another shot can be placed quickly. I primarily shot it through a 6mm using Superformance powder and pushing it at an average of 3812fps. I don't shoot many past 400 yards, and very few past 500 yards so that probably makes me lean toward the mid-weight bullets a bit more.
The 75gr V max performs similar to the B tip but exits a bit more often. I've killed a bunch with it though, it's a darn good bullet.
The 85gr Sierra Gameking is a darn good bullet too, great performance when they hit a deer or coyote. I just always wanted a little more BC when going that heavy and giving up that much speed.
The 85gr Speer BTSP is a good one. It performs similar to the Sierra but has a better BC. It will exit and tear up a coyote, but it dumps them. I used it last year in a tournament once the wind picked up and got 4 with it. I shot a triple with my 243 bolt gun on one stand when the surviving coyotes picked the wrong way to sprint off after I dumped the first one. I ranged my pack from each coyote when recovering them and I got them at 60, 120, and 170yds. I shoot a lot, but luck played a pretty good part in that one. Tournaments I usually have a 12 gauge, AR, and the 243 bolt gun in the truck and will switch between them during the day depending on the set and weather. I don't want to call in a bobcat while packing the 243 with the 85gr Speer, but it can be just the ticket in open grassland. I sometimes get coyotes my partners have missed as they sprint away and this bullet will hammer them from any angle.
The 90gr Accubond and 100gr Gameking have done well also, I just don't see a big enough BC advantage to offset the velocity loss at the ranges I shoot. If the coyotes get that far out or the wind gets that bad I'm going to be packing my 264 win mag and shooting 140 or 143gr bullets at them.
I ordered a box of the new Sierra Gamechanger 90gr bullets. I might just go heavier for that one, it has a BC significantly better than the 90gr Accubond. I have a 1 in 9 twist 6mm that might shoot it well, I'm not sure if my 1 in 10 243's will.