These were my favorite brand. A close second would be the Target brand storage bags. But these are nice and feel solid.
Also, for new moms who may not know anything about milk storage bags, the storage bags don't have to be the same brand as your pump. You can essentially get whatever type of bags/containers you like.
Here are some things that I liked about these bags:
-they are sturdy, tough feeling bags. It doesn't feel like they are about to rip
-they have double zippers to prevent leaks
-the bottom is sturdy and helps to try to stand the bags (although I wouldn't trust any bag to just stand as I pour my milk into it. I find it unfair that other comments for storage bags complain that they lost milk due to them trying to do it one handed and stand the bag on its own. It really isn't that difficult to hold open the bag with one hand and then pour the milk into it with the other hand. my point here is that it makes holding the bag open much easier when the bag isn't flopping around)
-the volume measurements are pretty accurate
-it's a good price for what you get