Head makes the best quality bags for flight I find. Pretty much all the guys I know that play futures use Head bags for long distance travel and they hold up well. I really like their Monstercombi's since I carry so much garbage with me to tournies.
I've used a Babolat bags for around 4 years up a few months ago. The 9 packs are too small for my needs but they are well built bags. I can fit 2-3 thick beamed sticks in the thermal compartment, and most of the other stuff I need in the other. It's a decent set up but gets heavy for any long distance walking haha!
Definitely go big if you think you'll need it in the future. 12 from pretty much any brand will good and should last you a while. I thought I wouldn't need a bunch of stuff, but then I realized how much I actually carry around with extra sets of clothes/food/water etc.