Simia for me. The mouseover targeting is awesome, I get about 10fps more than elk, the rotations perform just as well (despite being just 1 or 2 devs), but best of all, the devs are friendly and generally polite. You can talk to them, ask questions, make suggestions without the petty mood swings of the elk devs. The fact it's just 2 devs also means there's far less friction between them - something which drove me away from elk in the first place. So much arguments and bitching.
Definitely gonna stick with simia.