My personal inclination is to chase down every possible signal... That would require a large antenna or perhaps multiple antennas. That would in turn, require a heavy duty mount... If you're choosing to limit your choices to what will fit on the existing J-pole with little risk of wind damage, you still have a number of good options available. You'll want an antenna that covers both the UHF and at least the High-VHF bands. Here's a list of antennas that fall into a generally similar category
Antennacraft HBU-22 & HBU-33
http://www.antennacraft.net/index.html
Antennas Direct C2V
http://www.antennasdirect.com/store/uhf-vhf.html
Channel Master CM-2016 & CM-2018
http://www.channelmaster.com/default.asp
Winegard HD-7694P
http://www.winegarddirect.com/
Start with an antenna aim of about 160°, then adjust either direction to find the best overall reception.
You can reuse the cable left behind from the Dish install, but be sure to remove satellite system accessories such as matrix switches, diplexers, power supplies, etc.
You may need an amplifier, but I would install the antenna first, verify it is able to drive a single TV with no splitters or other accessories. Then add a 4-way splitter, with one port feeding a 2-way splitter... be sure to place the 2-way after the 4-way. The outputs of the 2-way will be lower in level so use those to drive the shortest cable runs.
http://forum.tvfool.com/showthread.php?t=13090
If you find that you loose one or more weak signals, you can add a Channel Master CM-3410 distribution amplifier between the antenna and input of the 4-way splitter.