Best/ Smoothest Zippers what do you use?

I've made four projects using zippers (amy butler sophia and her make up bags, made by rae back pack and a boxy tote. I've been using the old standard coates (sp?) poly zippers and I keep telling myself to find smoother zippers.

What brand (and style - plastic/poly/metal) of zipper do you use for your projects?

Where do you buy them?

Thanks!!!!!

I usually buy YKK invisible zippers. (Nice to have on hand in a few neutral colors.)

I do sometimes use the Coats & Clarks from the local store if I'm pressed for time and don't have the right kind on hand. They aren't bad but I prefer the YKK in any style. Never had to replace a YKK, even on stuff my mom made years ago.

I have been buying from http://www.zipperstop.com/ for a long time, very good prices, especially if you are willing to buy by the dozen (totally worth it). They have a kooky website but I've never had a problem ordering and they also have an eBay shop also with good deals on single or bulk. They have pages of zippers just for handbags! As well as any other kind of zipper you could need in any length. Also other hard to find tailoring notions.