DK + RShaman arena comp?

Hey guys, my friend is gearing his resto shaman right now, and we're thinking about playing some 3s. I'll be playing a Frost/UH DK.
I know that almost any comp works at lower ratings but, which one would be the best one to start? Rshaman/DK/?

Thanks :)
shadowcleave, Restoshaman / afflic lock / unholy dk

i know that spriest / unh dk / rsham works too, but it's not as good

i'm also pretty sure resto shaman / sub rogue / frost dk is a good comp too.