AAPL: vertically integrated.
Best of breed hardware, and leading online services. (Not sure why Xaiomi gets away with calling their App Store online services, and Apple can not.)
Slowly integrate key services into its ecosystem. (Which seemingly goes unnoticed or unappreciated by users and investors.)
Building out services targeted to their ecosystem. (ie iRadio) Although, I would love to see them go horizontal with iWork, maps and iRadio. (Those that ads can be placed or software to be purchased.)
iTunes user base is north of 500M.
GOOG: provides horizontal services (and understand the concept well), but can't make up its mind on vertical integration.
They have the know-how to produce interesting hardware, but lack the capability of distribution and mass adoption.
Google seems confused with respect to the vertical. At the moment the market is forgiving of its confusion. But the lack of clarity will start to really affect margins. When the margins hit affects the expectations, the stock will get hit and Google will have to decide what it wants to be.
MSFT: horizontal, but voluntarily limits its services. And allow great properties to get passed up by newer players. (ie Skype-to-WhatsApp)
With their re-org, and purchase of Nokia, they can be truly vertical. Limiting their services now makes sense.
They have changed their mobile strategy more times then I care to remember.
They in a mess right now. First few steps should be to
1. Improve their mobile OS UI.
2. Keep their services relevant.
3. Like Google, decide on vertical or horizontal. (But looks like they currently chose vertical.)