Welcome, Josh!
"General Modeling" is always a good one because it gets a lot of traffic.
"Painting and Airbrushing" seems to as well.
Others are pretty dormant. You should train yourself to always read the date of the last post. A common mistake made by new members, no big deal but you'll get ribbed for it; is to repond to a post that's five or six years old with a conversational answer.
Check though is a good way to see how often certain sub forums get looked at.