The average gain of the HBU55 is VHF 9.3 and UHF 9.0 . The average gain of the HD7698P is VHF 11.5 and UHF 13.7 . The gain of 2 more at VHF is not that important . However a gain of 4.7 more at UHF is important . As to length and price. 12 feet and 14 feet . $68.00 and $111.00 at solidsignal. Well it's your choice. . Here some ways to get the antenna/s higher.
http://www.ronard.com/Tripods%200703/4712.html. . And very nice high quality light weight aluminum layover towers. Do antenna installation and adjustments standing on the ground.
http://www.palcoelectronics.com/pe300.aspx