When it comes to loopers my preference is tc electronic. I had a standard Ditto for the longest time, which I gave to a firend, he still uses it. I have the Ditto+ since its release. I love that thing. I also have a Ditto X4 that I used alot when I got obsessive about looper some years ago. That phase passed and I just use the Ditto+ now.
I wanted a "cheap" stereo looper for my the practice board. I want to send a bass guitar to one side to a bass amp and the other side a guitar going to my guitar amp. For times when its just me and the drummer getting together for a session. Having the super basic drum sounds, is great for when I get there early and jam by myself.
I chose the Nu-X as I wanted all the features of the Boss but didnt see the point in spending the extra € on the Boss, especiall as it wont go through any rigorous use. I also have a friend who has a Boss mono looper and I did not like using that at all.
I have had many Nu-X pedals over the years and have been lucky to never have any issues with the quality. There are pedals I did not like tonaly etc and sold them, but never had any issues with quality. I have at least 15 Nu-X pedals in my pedal locker or in use on boards.
The Nu-X Looper has surpassed all my expectations and works exactly as I had hoped. If down the road, like 2+ years, it turns out I got a dud and it dies on me I would be happy to replace it. I've had Boss and other reputable companies pedals die on me too over the years so it is what it is. But I'm not worried about that happening. The quality of Nu-X is up to standard in my opinion.
However, if I was going to gig with a stereo rig and wanted a basic compact stereo looper. I would hands down buy the Ditto Stereo Looper.
The Ditto X4 is just too big for a board that already has 6 to 10 pedlas on it. But I will never sell the Ditto X4, its too much fun.