I saw a solo artist using a BOSS RC-300 to do some very impressive multi-track looping. Turning on and off percussion (made by thumping/strumming), another loop for "fake bass" (using an OC-3, his only "pedal"), another for "fake electric guitar" (his only instrument was an acoustic), and another loop or two for rhythm sections. And turning all of them on or off, real time, during a single song. It was impressive.
The key, in my mind, is how many separate loops do you need instant button access to? If no more than two, then the RC-3 (with optional FS-6) or something like the Ditto X4 should do what you want. But unless you are sure that 2 is the max, then even that won't cut it. I was blown away with what this guy did with the RC-300. If I really wanted the maximum flexibility for looping, that unit is now at the top of my list.