The JBL Charge 3 sounds better with more bass, a well balanced full range sound, gets louder, and has more battery life.
The UE has a good full range sound but less bass, and is omni directional. If you want to place the speaker in the middle and hear all around the UE is the better buy. If you can live with a standard speaker you place in front of you then the JBL is the all around winner. Being omni-directional is the only thing the UE beats the JBL at.
Lets say you are at the beach and you place the UE in front of you. Everyone around you will hear the speaker. With the JBL you can point it at you and not everyone around you will be hearing it. Maybe omni-directional is a bad thing if you don't want to disturb people around you. Your call.