Perception of stability.
Which until recently, was relatively unshaken.
As an employer, MS also has tended to be much more understanding of personal circumstances and the likes - I know people there who took long career breaks, or had mental issues/breakdowns (sometimes quite public) that would elsewhere have been a resume generating event.
Locally Apple are also regarded as an extremely stable employer, especially at the lower levels (support, etc).
I've friends working fucking customer support jobs at apple because its stable and comfortable, when they could be making twice as much elsewhere given their skills.
I considered taking such a job a couple of years ago, after becoming thoroughly burned out of consulting/contracting and wanting some stability.
Funny thing about Apple though is the IP clauses in their contracts.
Even the guys working phone support for customers have to go through a whole paperwork process if they want to publish code they wrote in their own time online, just to ensure there's no Apple IP in it.