I own a Skytrak. Do not use it a whole lot, but when its rainy or cold outside I will hook it up to a sim I built in my garage. Have "The Golf Club" on my PC that I use as my sim software. A ton of fun. For the money its a really good device, but its not great for outdoor use and is limited in what info it gives. Its the low end of the highest grade monitors on the market.
The Foresight GC2 (IMO) is the best launch monitor out there that does not cost $15k+ I believe you can get a new one for $6-8k. You can easily use it outside and it gives enough data and solid numbers that any golfer would need. Most pro shops use it since its much cheaper and as accurate as the more expensive monitors out there.
Trackman gets all of the pub, but Flightscope has outperformed it in tests and is cheaper. The GC2 should come down in price since they are releasing a new unit this year that will rival anything on the market now. You can find a used one somewhere on the net for a good price. To be honest, if I could go back that is the option I would have taken so I could use it on the range more and not just in my garage.
Zepp and others are more swing mechanics technology. Launch monitors are mainly used to show your numbers and ball flight. If you are working on your swing my advice is to use the money on a PGA Pro and not a bunch of tech junk. I bought the Swingbyte and its cool at first but you soon realize it does nothing to help your swing. A trained eye/video analysis is much much better.
