A single combination antenna may work. My preference would be two separate antennas, one UHF and a High-VHF.
For UHF, the Antennas Direct DB4e stands out. It has both gain and broad forward beam-width. Both factors are helpful in your situation. The Antennacraft Y10713 and Winegard YA1713 are very similar, either would be appropriate for High-VHF.
By using two antennas, you'll have the ability to fine tune the aim of each, which improves your chances at reliable reception of more stations. For UHF I would suggest a starting aim point of about 215°, for H-VHF about 220°. Adjust each to maximize reception reliability. (Of course, the UHF aim will affect real CH 14 and higher. When adjusting the H-VHF antenna aim you'll be optimizing real CH-8, 10 & 12.)
An UVSJ will be needed to combine the two antenna outputs into a single down-lead. An Antennas Direct PA-18 or CPA-19 would be my choice for a preamp.
http://www.amazon.com/gp/product/B00...pf_rd_i=507846
http://www.amazon.com/AntennaCraft-1...eywords=Y10713
http://www.amazon.com/Antennas-Direc...f+vhf+combiner
http://www.amazon.com/Winegard-YA-17...eywords=YA1713
http://www.amazon.com/Antennas-Direc...keywords=PA-18
http://www.amazon.com/Antennas-Direc...eywords=CPA-19
A single combo antenna such as the Winegard HD7696P would be an alternative to the dual antenna system.