No such thing. Some will cover frequencies and systems not use in your area, making them a wastre of money - even though their coverage may be the "best." Some are simple to operate, some are very difficult, so the "best" will be determined by your experience and expertise at operating such devices. The Uniden Bearcat BCD396XT provides the most coverage, including trunking systems and digital systems, but it may or may not be the "best" for your area or needs.
One can find police scanners when one goes to a store called Scanner Master. This store carries police scanners made by Uniden and Bearcat. Price varies by brand and model.
The best place online to listen to online police scanners is onlinepolicescanners.org. Listening to the police scanner online should not damage your other scanners.
There is not always a "best brand" of receipt scanners because each brand has its advantages and disadvantages. Common brand names are Epson and NeatReceipts.
Police scanners check for police radar beams so that a person knows whether or not they are being monitored. A computer scanners scans a physical document and makes it into a computer document.
Cheap scanners are produced by Canon. You can purchase Canon scanners for around $50. You can purchase these scanners online from stores such as Walmart.
Police scanner let's you listen to police radios and NASCAR scanners are scanners that let's you listen to NASCAR team chatter
radioreference
the best brand of 9 mm that the police use is the glock
Most of the desktop scanners in use are flatbed scanners. The HP is brand leader in flatbed scanners. There are other companies like Cannon, Xerox or Fujitsu also produce reliable and high quality scanners.
Specialty hobby and electronics stores such as Radio Shack carry police scanners. Additionally one can buy police scanners online from ScannerMaster and Walmart. There are a number of apps for smartphones that also act as police scanners and many local jurisdictions are now broadcasting their emergency channels over the internet as well.
Modern police scanners are accurate to with about 3 mph.
Police scanners are radios that monitor the police channels on the police radio. You can hear the officers being dispatched to calls and hear them talking back and forth. Be aware, however, that since 9/11 most big-city police radio channels are now encrypted and cannot be monitored.