Valentine 1 is no doubt the best, but SUPER expensive.
I had a Passport 8500 x50, which worked fine.
The New Passports, 9500, are pretty nuts. Built in GPS tells you shit like someone a mile ahead of you just got hit, you can mark locations of common speed traps, stuff like that.
The only issue is with Laser. Some have shifters or jammers or whatever you want to call them, but I've heard that's pretty reliable. As long as cops are using Radar instead of Laser around you, you should be fine.