I've been here before.
I was in the market for about a £400 dock a couple of years ago just before the Zeppelin Air came out. I trialed the Bose SD 10 and the Zeppelin and while on first listen, I thought the Bose sounded great, after listening to a variety of music, the Bose got tiring very quickly. I couldn't get to grips with the bluetooth thing either. Seemed to sap my battery like nothing else and not sound anything as good.
As for the Zepp, it want the Air version so didn't have the wireless facility but to be honest, I was buying for the kitchen so didn't really need to be able to stream music from my iphone in the lounge to the dock in the kitchen.
Sound wise, after a period of listening, I just found the Zepp much more musical and a pleasure to listen to. If I were to buy again, I'd buy the Zepp again and again. Obviously there is the Zepp Air now so you get the advantage of Airplay but bear in mind that they are apparently a bit of a faff to connect to your wifi. Once connected, they're meant to be fine. Also, if you're buying new, this shouldn't really be a problem as the firmware was changed in reaction to these issues. If not, you can always flash the firmware really easy through the app and usb port.
Another thing is that when the Air came out, it wasn't just adding airplay; B&W changed the whole innards and drivers of the unit, making it sound better yet. It's now a fully discrete bi-amped system! I'm not sure what updates the Bose has had in it's lifespan since I was looking at it a fair few years ago, if any.
Finally, the Zepp just looks so much sexier in my opinion!
Have you looked at the Arcam Cube? Not the prettiest, but meant to be the best dock out there at that sort of money.
MY14 Space Grey F11 530d M-Sport