Eric brings up some important questions. buildings and mountains will make the job nearly impossible.
I recommend the Shack because their antenna isn't too expensive and they should be pretty good about returning it if it doesn't do the job for you. If there is a Channel Master dealer you can get to, they make good stuff too but I prefer the corner reflector design of the RS model. In my experience they are more directional and thus better at preventing ghosting.
BTW, AntennaCraft makes several models just like Channel Master but if this is your first try at an outdoor antenna and you don't have neighbors who will let you look at their reception to judge their antennas I like being able to carry an unsat antenna back. Shipping on these beasts isn't peanuts (compared to their price). You wouldn't want to spend 15 bucks each way on a 50 antenna.
One last thing, if a rotor doesn't work for your household, you can connect multiple antennas together to cover more than one transmitter site.