Mischa and Mini - Mischa definitely, so male
Smudge and Nutmeg - Smudge, fo sure, so again male
Now they're in a trio it seems to be Smudge -> Mini -> Nutmeg. I always thought Mini was the dominant one but Smudge chases both of them away from the food bowl now. The girls grab their fibafirst sticks and run away and eat and he gets top table by the bowl.
So with mine it always seems to be the males in the group. When bonding Mini was definitely trying to be top bunny by humping but Smudge seems to have settled into the role now.