I'll give you the opposite advice. 2 pounds for a +15 bag is pretty good. You have an entire other pound for that synthetic bag, and it will also not pack down as small. The price is also quite good for what you are getting, so I'd say bag number 1.

Yes, if you figure on getting it wet and sleeping in it, the synthetic bag is better. Don't get it wet, and buy the down bag (my feelings on this subject are already known).