I would go for the Jetta, but look for a lightly used '09 instead of the "new" 2010.
While the Golf and GTI are built on the Mark VI platform, the Jetta is just a face-lift with some interior pretty bits. All the bits you can't see are absolutely identical to the '09, so you're paying a premium for some very superficial changes.
It drives me crazy that most motoring journalists have not really highlighted this situation. I guess most people wouldn't notice anyway, but it's a bit disingenuous of VW to claim the JSW is as new as the Golf and GTI.
2010 E91 328i xdrive. 6MT, Sports, Premium Sound, Navigation
2010 VW Touareg TDI, 2006 E90 330i, 2004 E46 325iT, 2003 MINI Cooper S (Retired)