The best model will depend upon what frequency ranges it needs to cover.
The Remtronix Brand gets high ratings for 700/800Mhz.
Minimum +6dB Gain over standard antenna Flexible Whip rubber ducky design Excellent for Handheld Scanners & Ham Radios High Quality and Competitively Priced Engineered and Made In Japan Over 35K sold through OEM & REMTronix brands REM-810S/REM-820S Uniden SDS100 compatible REM-830 Uniden
www.remtronix.com