It is very hard (impossible) to answer questions like this without knowing more about your taste. Of the three, for me personally, I would see Pippin. (I haven't seen If/Then yet. The first NYC preview is tonight.)
I saw IF/THEN in DC toward the end of the run... and think there is great potential there. Pippin is the guaranteed charmer, since it's a proven entity. I didn't see Bridges yet, so can't say much there.
If you don't get to NYC often, I steer toward seeing OBC versions, and my personal taste would be If/Then over Bridges. Idina is giving a powerful performance here, and her 11 o'clock number is killer. You've got the Rapp/Dazeem/Grief Rent angle. The N2N dream team angle. And the only original show of the bunch (Pippin is a revival, Bridges is a book and movie). Even if the show isn't a hit, and they've changed a lot since DC, AFAIK, you'd be hard pressed to find more wattage and potential.
I am someone who traveled from NYC to DC specifically to see If/Then, of course, so keep that in mind, as well.