Hey there..
forget the JPole unless you are looking to build an antenna
the JPole is a so so ok antenna..
my suggestion would be more a high gain antenna..
Forget the GP-3 mentioned before..
Forget the Dimond antenna mentioned (it is same as GP-3)
i have friends using all 3 of the antennas mentioned so far and of those 3 are so so antennas...
seems best of those 3 are a simple JPole..
even so if you are going to use a roof-base antenna
I use a Comet GP-9 dual bander that has worked very well for last 4 years or so (the GP-3 and Dimond antenna mentioned i have found to be poor range antennas)
the Comet GP-9 antenna i use is about 18 ft tall with 8.5 Dbi on VHF and 12.6 Dbi gain on UHF
here is link to my antenna and the GP-3 talked about earlier
http://www.cometantenna.com/products.php?CatID=1&famID=5&childID=4
However if i was looking to get an antenna now
i would instead get the Better Dimond dual bander think it is the Dimond XNA-700 which is about 24 ft tall and offers both better gain and better lifespan and antenna durability
http://www.rfparts.com/diamond/x700hna.html
but even using my Comet GP-9 i easily hit repeaters 120-150 miles away (when i use 5 watts or less) and about 300 miles using 50 watts (though i rarly look for repeaters that far out)
i have the GP-9 mounted at 52 or 54 ft at the base
it has survived some very bad storms..
but seeing i am always looking for better antennas i would if buying one now get Dimonds 24 ft dual bander
though you dint ask about beams
I use Gulf Alfa Antenna beams
dual polarity 9 element on about 18 ft boom 2 meters
12 element horizontal 12.5 ft for 1.25 meters
16 element horizontal 12.6 ft beam for 70 cm
only beams perhaps better would be those of M2 (maybe)
Later