which one is better?
both are great but I would recommend the Unleashed if your just learning how to loop.
if you can loop pretty well already go with the loop900s
Well they play really well, but Unleashed is cheaper. But the Loop 900 has a changable gap.
Neither is better, neither is worse. The 6$ more gives a changable gap. The Loop900 is 2 grams lighter but that makes almost no difference.
I have both, and I would highly recommend the Unleashed. It also has an adjustable gap, just a different kind then the 900’s, and the weight really does make a difference when it comes to looping.
I think the 900’s are really good loopers, but their adjustable gap still needs some work. Plus needing a key to adjust the things can just get annoying, one extra piece to loose or strip.
JerenB - just got my Unleashed - what am I missing as far as adjusting? How do you adjust the Unleashed? Just loosen it up, or is there a trick? Thanks.
As to the OP:
I’ve been exploring these loopers (and modded Raiders) - between these two I started with the Loop 900 - if it’s good enough for John Ando 
it did take some dialing in - which is blessing and curse - I love the idea you can tweak on the fly, but it takes a little patience.
I just recently got an Unleashed - if anyone tells you they’re the same - I don’t think so, sure they look and feel the same, but not in the handling department. The Unleashed (proper name) seemed way speedier then anything I’ve used. This guy just buzzes.
Just my 2 cents - I like how the Raider flows, mostly because its heavy; so if either the Loop900 or Unleashed feel a little light, check them out. Bummer on the raider - you need to at least swap out the metal spacers for plastic (and its worth while sanding them down a bit, or use YYF spacers in them)
As for my taste, I really like the speed of the unleashed, and it will be my go to looper.
The Unleashed has an adjustable gap by slightly unscrewing it. Just a tiny bit! Adjust to tastes!