Here's a few things to consider: If you're going to be carrying a scope around as part of your regular birding regimen, consider a binocular you can one hand with some degree of pleasure and function. I would go with an 8x over a 10 for that, the lightest one, as well as the widest field of view. That speaks to the Zeiss 8x42, in the ones you mentioned..
I've been using a 10x42 for the past year, but a few weeks ago, started carrying a scope on a tripod over my shoulder. I moved to an 8x42 SF to make it easier to still get onto something without putting the scope down. I couldn't do it effectively with the 10x42. A 10x42 is great on its own, but you don't need the magnification if you've got a scope. Of course, your terrain, patch, wherever it is you bird, will tell you what probably will work best for you.
But if you're hauling a scope around, think about a wide field, lower mag, and less weight for the binocular, as the scope will cover the other end.
All those products you mentioned are excellent performers. It comes down to more what you're willing to haul around, and what is the best combination of tools to extend your reach. (widest field, greatest mag, etc)
Enjoy!
-Bill