Enhance is 200% more viable and easier to play than Ret.
As you mentioned you're only playing casually so I'd definitely recommend Enhance. You also mentioned you wanted to play with a feral, I remember feral/enhance being absolutely ridiculous in 2s at the start of WoD, so it's probably still viable, at least I'm pretty sure it will be at low MMR.
There's a lot you have to deal with if you're playing Ret, especially in double DPS 2s, since you bring a lot of utility/healing, which I can imagine would make it quite hard to learn if you're not playing much / seriously.