Uniden and Cobra are both good brands. You will be much happier with a radio that is installed in your vehicle than a handheld radio.
Buy a decent mid-line radio from a good brand and have it peaked for maximum range. Then invest in a very good antenna, which makes a big difference. Don't mount the antenna parallel to to another metal surface if possible -- you'll get much better range.
I'm a fan of this place:
Radio Service Center
918 South Sheridan Boulevard
Denver, CO 80226
(303) 922-8107
The nice thing about buying a CB radio from a place like this is that they can tune your radio for maximum performance. You buy a new radio from them, then pay an extra fee (like $30) for them to open the radio and tune it up. You'll have better transmission power than a stock, out-of-the-box radio.