Avent, pigeon, lansinoh and the tommee tippee ones are the better ones but come at a higher price. I dont really use a fixed brand as I inherited the various brands milk bags from other mummies.
I like using isa uchi milk pouches. I can pump directly into the bags and store rightaway.. Dosent leak too..
Super Mum
Sunmum! The triple zipper is really useful, the other brands I used usually have leakage problem...