We have a thread on this about every three weeks... it's like a bottomless pit of aviation shopping.
Zulu has a slightly more modern design and a trade-in offer where you get full refund on your old Lightspeed headset, assuming you have one, toward a pair of Zulus. Bose needs to drop their price $200, update the design, and also match the trade-in deal. More important than all of this is to make sure whichever one you go for actually fits well before you are committed to a purchase.