I own the Escort Passport 8500 x50 and it is amazing. It has the best radar detecting range I've ever seen.
The Valentine 1, Escort 8500 x50, and the Escort 9500i are at the top of the radar heap in my opinion. So which radar should you get? Its a matter of personal opinion. For me though, the Valentine 1 just looked like a dated piece of 1980's technology, so I went with the 8500. At the time, Escort had not released the 9500i yet, and the 9500i is supposed to be the king of the hill as I understand it. The 9500i is everything the 8500 is, with GPS built in. This allows you to "mark" false positives (gas stations, alarm systems, Walgreens, etc) so they will never go off again. So what happens if a cop parks in a lot that you marked as a false alarm? The 9500i detects the NEW signal in the area, and will warn you of the new "change". Simply amazing in my book.
Only con of the 9500i? Its expensive! $449.
As for my opinion though, I can personally vouch for the Escort 8500 x50. 150%.
I would buy another in a heartbeat.