I prefer RockAuto and Summit for the general purpose sources of parts. LMC is excellent for those specialty items not generally in the channel.
Rockauto (rockauto.com) generally will send/email you coupons for a discount, has good selection and fitment, and often best or second best pricing. I use them a lot for OEM replacements (GM stamped, anyway). Downside is the shipping costs depending on which warehouse the parts are in and where you're located.
Summit (summitracing.com) has IMHO a smaller selection, but a greater focus on aftermarket hop-up part and accessories, more go-fast items.
Both of these shops have been very response and provided good/great service. An ocassional slip w/ the wrong part, but they work with you to sort it out.
I've scrounged several local j-yards for some stuff, and touch the parts/pieces before I do the tear down.
Often resort to ebay for some stuff -sourced my door handles and window riser motors there - parts are still working and prices were decent.
Personally, I try to avoid amz - nothing wrong with their services/prices per se, but their business model seems to be focused on destroying all local businesses (Highlander model, there can be only one retailer.) YMMV.
