Both JBL speakers produce amazing sound for their size, and they are the best choices on that list.
We have all of those speakers on display at work and the Bose offerings are absolutely rubbish, I could not ever convey to you just how shite they are. They sound terrible, tinny, and they are incredibly overpriced just because they have a bose badge.
Both JBLs are indentical in terms of the sound they produce, they literally have the same speakers and specifications (and both produce great sound for compact units). The Charge gets a way longer use on battery life and can actually be used to charge other devices by USB. The Flip 2 is incredibly value for money though.
Thanks a lot for the valuable input. Although I have bought it already, your post il help all the future viewers who is searching for same type of speaker like me.