I guess I can be proud to say I use the sawyer bags that come with the filter because, free?, and never broke a one.  Some of them are years old and I did get rid of one because the outer layer started to peel off.  I wonder if the plastic is contaminating me.... 

I've found that as long as you realize that even though it's a "squeeze", the real bottle neck is the speed that the filter can filter at.  If it's running slow, you should really back flush the filter.  I do carry a water bottle that I can use where it's hard to get the water in the bag and some backup water purification drops to clean out the bottle when I want to use it to drink from.