I've used my Garmin a few times on flights. I have the software at home so I can upload the trip and see exactly where I was. Each time I've used it though I asked the FA if I could. The only time it was more than "yes" the FA just wanted to ask about how it worked.

As to which one will work better. They all work about the same. The only difference are the bells and whistles that they have. A $99 GPS works as well as a $900 one. As long as you can stick it in between the window and the shade you should be able to get enough signals to get a lock.