I agree with darrel about the 2wd but for different reasons.
You stated that you are new to RC cars but not to RCs in general. 4wd buggies are my favorite, but it was only after years of 2wd that I got into it... 2wd are a great start, and there are number of vehicles to choose from that are really high quality... They are generally easier to work on and generally have a lot less headache...
But if you must go with a 4wd and choose one, I would have to agree with many of the posters on here about what your local track/shop supports. If you're in the US, chances are, they probably support the Associated's stuff...
But check first, since one out of the three hobby shop near my town swear that "B44s aren't very popular." A very twisted view in my opinion...
My vote would go for the B44. It's a competition-ready, race-grade buggy out of the box. Even if you choose not to race, it's ready when you are...