I got a Suntour AR rear off of a 48cm Nishiki that I got for parts. I put it on my Peugeot before making it a fixed gear, and it quickly became my favorite derailer. Smooth, silent, and very easy to shift correctly. There was no fumbling around with trim or anything with that.
That being said, I put it on my g/f's road bike, as she hadn't ever ridden a roadie, nor had she ever used friction. As ham-fisted as she was at the beginning, even then it never ever chattered. Amazing stuff.