Here is a great site for dash cam info
http://dashcamtalk.com/dash-cam-comparison/
I am running DVR 027 myself and its been great no issues. Only cons in my book are 720p HD, and size of the mount. I managed to make a custom mount so now its just the HD quality issue. These things are dirt cheap I have found a couple for sale for 17 bucks!
I just bought F900LHD just so I can have a camera as well if I ever need to take pictures in the event of a crash. This one has gotten good reviews as well but once again size seems to be the biggest con for it. This cam does it all tho and even has the motion detect mode like a lot of the higher end ones. This is more expensive than the DVR 027 but I still found one for only $70. I will review it and post up some sample vids when it comes in.
The BlackVue looks great and the sizing is prefect but many have reported heat issues as well as image quality lost after a year of ownership.
For Radar I just picked up a Escort 9500ix Race Edition and its saved me from two tickets so far. Works pretty good however you must remember it is a
radar detector and not a cop detector their radar must be on for it to alert you. Its also handy for letting you know where redlight cams are located.