best detector period: http://www.valentineone.com/
I am not very familiar with the laser scramblers...the one ticket I have gotten was with laser from an overpass in Wisconsin.
Speeding tips...radar detectors are just about useless if you are the only car on the road. Most cops these days use instant on so you have no time to react. You really need other traffic so you pick him up shooting other cars before he gets to you. So if you are in a rural area with not much traffic a detector may not be very effective...and may even cause you to get more tickets...because you will likely speed more and you will not talk your way out of a ticket with a detector sitting on your dash.
Take small K blips seriously...if you get one small blip from the detector that is likely a cop up ahead using instant on other traffic...slow down. If you get a laser blip slam on your brakes because a car within 50 feet or so of you just got laser-ed (it is pure luck to even pick up stray laser signal).
Still the best radar detector are your own two eyes. For a cop to detect you...they have to be closer than a 1/4 mile...on the highway you can easily see a mile ahead.
Detectors all pretty much suck in city environments as even the best detectors pick up a lot of false signals. the only time I find a detector worthwhile in the city is if it is a route you take all of the time and you learn all of the places for false signals. Personally I only use my detector on hour plus highway trips.
Depending where you live/park having a detector can be an invitation for someone to bash in one of your windows. Never leave your detector up, wipe off suction cup marks (thieves do look for the tell tale suction cup marks and can often tell what kind of detector you have just from the spacing and size of the marks), and even then a lot of thieves will follow people with detectors to where they live/park and bash the window looking for the detector even if you remove it from the car.
Another negative about a detector is if you are good at talking your way out of tickets once you have a detector sitting in your window you will not have much luck talking your way out of a ticket. Cops love to bust someone with a detector.