I have a cobra 97xx series. Bought it for like $115 on Newegg. Works great.

From 2.5 years of having it: I've been hit with Laser 3 times. Twice on 75, once by a sherriff on McMullen Booth Rd.

X band I totally ignore.
Same with POP. X and POP make lots of noise on the interstate from every 10-15th truck you pass. Also some garage door openers pick up on the X.

I'd rather have a radar detector that is really sensitive and gives false alarms than something that misses. Anyway, I also find:

Sheriff's usually use K, but I've picked them up on KA before.
Ku you'll probably get in podunk towns, if there anymore.
Ka**** very important. FHP 100% of the time. Locals and sheriffs sometimes.

For the locals, it's a smorgasbord...basically depends on what they can afford I guess. Watch out for KA and K.