There really is no clear-cut answer to that question and I'm not going to recommend any one specific radio. The right scanner for you will depend on several different factors:
1) What do you want to spend?
2) What else do you want to listen to? (if anything)
3) How much of a radio buff vs. a rail buff are you?
4) Do you want a base/mobile unit or a hand-held?
After you answer those questions then you should be able to figure out what kind of radio will be best for you. I will say that both Uniden (Bearcat) and Radio Shack offer a full line of both base/mobile and hand-held radios in all price ranges. Obviously the lower-priced models will be more basic in their features and operation than the the mid and higher-priced models will be.
Personally I prefer the higher-level radios. Professionally I'm an emergency services dispatcher and have had an interest in all types of radio for as long as I can remember. My listening post at home is comprised of 5 base scanners and one hand-held for when I'm trackside.
Check out www.scannermaster.com
. They all offer great selections of Uniden and Radio Shack scanners.
I know I didn't offer anything specific in terms of a radio, but I hope I helped you to make your decision. Feel free to PM or EM me off-board if you have any specific questions.