Having had to work (loose description) with the Apple eco-system for the past 6 weeks at work, I'll go for anyone that isn't them. Clearly they're in it for no-one but the consumer - at least Microsoft cater (somewhat reasonably) for those who actually have to work with these devices daily. Apple have finally extended their DEP programme to the EU this year, but the actual process of trying to work with the multiple iTunes accounts under a single IP address is a miserable and horribly frustrating experience.
Like the consumer end of their business it promises much, but in our case, and I'm sure many others (ask anyone who's had to license apps to numerous devices) it's just stunted, an infuriatingly slow process and ultimately horrifyingly expensive in our case (a school).
Personally I wouldn't be too fussed if it's Google with their Chromebooks or any Windows-based device, but I strongly suspect Microsoft still hold the cards from a productivity point of view. Personally I'm not in the market for either though - I get by perfectly fine with my Windows PCs and Android phone.