I'm going to be a bit of an outlier here and recommend Regina Oro. I used to burn through a lot of freewheels and Reginas would last the longest. I know some people I respect here have mentioned QC issues, but I never had problems myself. The basic truth is the teeth lasted longer. Harder steel or something. Cyclo were good too. Suntour New Winner were OK. This is if we are talking very vintage freewheels. I didn't care for Shimano, but when 7400 came out in about 1985 they did more less pass everyone, and are still ahead.

For modern freewheels: Sunrace are quite good and reliable IME and cost very little. They're not that light, but neither were vintage FW. For something fancier, I know the first batch of IRD had some problems but supposedly the new ones are good. Haven't tried them.