In my years participating in these forums, it seems like I hear the most about Watts and Febco. I've at least heard of Wilkins, but not Conbraco.
I'd say go with the one that is easiest to obtain.
Me personally, I'd pick Watts just because that's what the big-box stores carry around here. You figure they are likely to be cheaper than any irrigation supply store, and quicker than mail order. If there is anything defective, it's a quick trip and no hassle to get a replacement.