I've tried a few synths and like a couple of them a lot. The Muhle STF v2 is comfortable, not too springy and whips up a nice lather. The Razorock synth knots are also very efficient. However, I wouldn't compare them to badger knots (which differ widely in any case) because they're just not the same beast. Badger knots just have that element of a bit of scritch and individuality that synths lack, for me.