You also might look at the Scorpion (http://www.scorpionantennas.com/antennas.html
). It's interesting for a couple of reasons.
In the non-screwdriver category is the HiQ. It costs more, but doesn't change lengths like the former ones do.
No matter what antenna you buy, mounting it is the real secret to getting performance. If you want more info, visit my web site.