http://www.theradarreflectorsite.org/RTE.htm

Practical Sailor has compared the various types. In the past Davis' inexpensive Echomaster was hightly rated. We had one a LONG time ago and it was a pain to rig because it tended to blow around in the wind. There are number of work-arounds for this to keep the things from windmilling.

Our Lensref, while no longer marketed, is now essentially made by Lun'tech (Scandanavian ;^)))) ). It isn't inexpensive, but was very well rated. We have it fixed to front of our mast about 50' off the water.