I don't know much about Windows Phone 8, but I'd imagine your app choices would be more limited due to there being less developers.
This was my main concern I guess.
I really like the Nokia Lumia, both for its design and the legendary durability of some Nokia models.
I've happily used, and recommend, DSLR Controller on my Nexus7.
No official wi-fi app for Windows 8 is in the works per Canon:
The spiffy iOS hardware enabler: http://www.camranger.com/features/ is priced such that I would rather just buy one or two Nexus devices and use DSLR Controller. And this from a family with one or two iDevices per member. (BTW, the latest DSLR Controller update included 6D and WFT support.)