For me, working in Carrara is faster, but I think that's a combination of having used Carrara on a regular basis much longer than I've used Poser. Carrara's scene manipulation is also just plain more straight forward than Poser's.

The newest Poser Pro (2014) has some nice tools for creating/tweaking content to fit just about any figure. It's fitting room (for fitting clothes to other characters) works pretty well. While it has more steps to go through than Studios/Carrara's autofit, I think it works much better. That's just my opinion. I just realized you said you had 2012. Except for the fitting room and a few other little things, 2012 can do most of what 2014 can.

Stan's right, Poser does have native dynamic cloth which Carrara does not have, but it can be used in Carrara. Studio's dynamic cloth is different than Poser's, and I do not know if it can be used effectively in Carrara.

Carrara's dynamic hair is much better than Poser's. You can style and manipulate dynamic hair in Carrara. You can't really do much of that in Poser.

There are a whole host of plugins available for both programs that extend their capabilities.

You can model Poser clothing in Carrara, but as Stan said you will need to go to either Poser of Studio to rig them (although I do seem to remember that there is a way to rig Poser content without having to use Poser. If you're interested, I can go through my old tutorials and see if I can find it). I personally don't find Carrara's modelling room to be very user friendly, but it does have the tools you'd need to create content.

It all really comes down to what you want to do. If you want to do landscapes, complicated scenes with lots of assets, special effects, etc., or animations then I'd go with Carrara. It's fast, responsive and very capable. If you want to do mainly character shots/portraits I'd go with Poser. It has much better subsurface scattering and it has the cloth room, hair room, and fitting room to work with as well.

I do use both programs. The project sort of determines which one I will use.