I personally like Yearone, even though sometimes they are overpriced. I usually make a list out of all the newly discovered parts I need and wait for a 10%/20% coupon to come in the mail. Another nice thing about Yearone is that they have a great online catalog that makes ordering simpler. I also havn't had any problems with the Paddock and would recommend them as much as Yearone. I also recommend this guy
www.musclecarparts.cc because he usually has good prices. Other than those places, most of my parts came from individuals on eBay.
If you need engine parts, then Mancini would be at the top of my list. I also recommend Summit Racing and 440source (if you have a big block). Mancini ships quickly, doesnt gouge shipping prices, and I have nothing bad to say about them. Summit Racing doesnt have a wide selection of Mopar parts, but what they do carry is usually the cheapest around. As for 440source, the only thing I have to say bad about them is the lack of ordering parts online. I have also dealt with Jegs and havn't had any problems with them. I don recommend them as much because you can get everything they sell from Summit Racing for cheaper usually. Another reason I dont recommend them is because I had a friend that had a very bad experience with them.