This is a terribly odd statement. Microsoft has shown, time and time again, that they can shaft their customers because many of them have, or at least had, few alternatives. Google might make a lot of its money on advertising, but it wouldn't make a penny if it didn't have the trust and respect of its customers.
I'm not sure I have that level of trust for Microsoft, though my trust in Microsoft is much higher than, say, facebook (which I actively distrust, and try very hard to prevent from having access to anything I would consider private, especially email).
Your email is likely to be an important part of your life's documentation, containing an awful lot of very personal information. An unscrupulous provider could use it in all sorts of horrible ways - off the top of my head, how about a lucrative employment screening service that lists of how often you've mentioned getting wasted the night before, or throwing a sickie, or dissed a colleague... let alone the value of strategy, customer communications and other immensely valuable commercial conversations.
This is why many here refuse to use email services they don't control. I myself use Gmail, because I trust Google. Not because they say "Don't be evil", but because I think they understand how their entire business depends on trust. Compare this to Facebook, for whom privacy seems to be an afterthought. Their business is being badly hurt because they continue to trample over their user's trust.
And what about Microsoft? For me, the rorts Microsoft have carried out in the past twenty years (cynically stacking standards organisations with their minions to bulldoze their document format through was the last straw for me) counts them out. I'll never use another MS operating system or online service, end of story. No matter how much better than the competition.
So for me, particularly for online services, trust trumps functionality - absolutely.
But no, I was talking about search. Google doesn't do email well in general. Their one significant advance was popularizing threaded display of conversations, and that hasn't been a gmail-exclusive feature for years.
Google is just as susceptible to trust issues as Microsoft or anyone else. Every time Google is caught violating privacy it's always an "accident", like with the wifi network data collection being done by their street view cars. If a company is constantly apologizing for "accidents" that align with their business interests I'd have a hard time trusting them, even if I continue to use them.
