I have the Kestrel
300 and the Minox Windwatcher (from Leica). I have compared them many times and have never seen any significant difference in the readings. The Minox is also sold under another brand name I believe, probably cheaper if it doesn't come from Leica. They are both nicely made, most guys prefer the Kestrel when they compare the two. Here are some thoughts on them for what it is worth:
..the Minox is significantly smaller in overall size, has a shiny aluminum colored plastic (?) case, has a smaller impeller that is not replaceable by the user, at least there is no mention of doing so. It has a carry string attached, does about the same functions as the Kestrel. Impeller (fan) housing turns so that the blades are shielded when not in use
..the Kestrel 3000 has a separate protective carrying case that the unit slides in and out of, uses repaceable fan blade assembly (impeller? which can be bought from Kestrel) and an oversize lanyard that is the only thing that I do not like. I store both units in an RCBS die box that has the little baffles removed, and the big boot-lace sized lanyard takes up a lot of room. On the other hand it securely holds the unit and case, and I could easily take it off and put on another.
Both units have two buttons to activate the unit and its programs, that is at least one too many for me. They are very nice for determining what the wind at your site is doing, tell you how strong the gusts are and what an average is. Also tell the temp but I don't know how accurately relative to a good thermometer, does it matter as they give you a pretty good idea. As I mentioned the two units are usually within one or two mph and one degree.