Justin Guitars has a great tutorial. He emphasizes the importance of hitting record right on the beat. Recommends playing a few bars before recording, tap on the 1, and untap on the 1. Also recommends using a metronome.That is why loopers are the next best thing to metronomes...
I had the same issue with loopers at first. Used a metronome with it and it made a whole lot of difference.
I definitely became a better rhythm player when I started using a looper. For the first few days, it was nearly impossible to get the timing right, but then it just clicked and it turns out I'm pretty damn good at finding the one - I seem to be able to dance around, skip a beat here and there and still nail the landing. I don't do anything fancy with them, usually just a basic rhythm track, maybe a bass track below it, and that's it - then just play to it.You're right. That's why I think loopers are great practice tools. I feel my timing is way better than before.
All the loopers sold on amazon, under Ammoon, Donner, and the other names i can't think of right now are the same looper, with different lables on them. They are all made in China and quality is hit or miss. Warranty is difficult to get or non-existant on these.I have an Ammoon Looper for under $50 from Amazon. Does the job for me.