I own both and would have a hard time recommending one over the other. The sound and feel of each are totally different.
Contrary to what the others here have seen, the build quality on my Gretsch is slighter better than my Jag SS...neck pocket is tight, fretboard is flat, fret ends are nice and smooth, the setup was spot on (had to set intonation on the Jag), and I love the finish. Such is mass production...
The Gretsch pickup is hotter, and is a little muddy compared to the Jag SS, but it sounds really good. I've tried switching out a couple of string sets on it trying to get better definition on the low E (stock strings, Chrome flatwounds, and XL medium roundwounds) and I think I like the flats the best...but this could change tommorrow...;-).
Definitely try to play them side by side if you can.