It depends on your preference.

For the same price, Odyssey has more standard safety features vs. Sienna has more stardard features for comfort. I like the run on 3 cylinders while cruising on Odyssey LX leather or Touring models (which increases gas milage), and spare tire storage on the wall (it allows you to use regular tire). In contrast, Sienna didn't have spare tire storage (at least 4 years ago), and it has to use a set of special tires called run on flat tires without a spare tire (because lack of spare tire storage place). This might be changed already. The problem with run on flat tire is that they are much more expensive than regular tire and you can only buy it from the dealer (no compitetion). They are heavier than regular tires which leads to lower gas milage. If you don't have to buy the all wheel drive version of the Sienna, don't buy it. It has very low gas milage. For $2000 upgrade from LX to LX leather of Odyssey, you get leather seats, extra center seat (to make it seats a total of 8), sun roof, and most of all, the run on 3 cylinder while cruising. It is worth the money.