I've had the Jet 1642EVS-2 (the 2 HP 220V version) for almost 6 years now and really love it. I've also had an opportunity to use the Powermatic 3520B for many weeks when taking woodturning courses at John C. Campbell.
The only reason I'd get the Powermatic over the Jet would be if you needed the extra 4" of swing over the bed (can turn 16" diameter bowls on the Powermatic and only 12" on the Jet). The Powermatic is definitely beefier than the Jet and is a more pleasant machine to use on large heavy logs. Other than that, I don't find any significant differences in using these two machines, which are made by the same company. They both offer similar features and are equally great machines when it comes to medium and small turning projects.
Ouch! I just looked up pricing. The Jet is now selling for double what I paid for it. It looks like the Powermatic is about 50% more than the Jet. If you're going to be turning a lot of large logs, I'd go for the Powermatic. If not, I'd save the extra money and get the Jet.