Humans who work at Google do not read your emails, humans who work for the FBI on the other hand do, Google and Microsoft too along with other are required to implement back doors for the law agencies, you should be a lot more paranoid about that.
If you want absolute security, you are not gonna get it from nobody, and that includes Microsoft. Any information stored on a server you don't own is not secure, any information passed trough the internet unencrypted is also not secure. If you want absolute security you need to make sure that the information that you want to send is encrypted when transferring and only gets decoded and stored on servers you own and know to be safe from anyone, in other words, don't use email at all, because it's not secure by design, most of the time, it's vulnerable to man in the middle attacks.
Shame on Microsoft for not competing with features instead of FUD.
I'd like to read more about these "required" back doors.
If you mean that they have to comply with court orders, then yes, that's a "back door". But companies that comply with valid court orders to release emails are actually protecting your privacy. If they refused to comply with the court order, the government wouldn't say, "oh well, we tried, too bad", they'd come physically take all the servers and disks that they thought could possibly be relevant. That means that the government would now have access to your email, even though you weren't the target of any investigation.
Ultimately, if you want privacy from government intrusion into your email, stop electing judges that will sign warrants for your email. You can't expect major corporations to violate the law to protect your email. It's just not going to happen.
Sure, Google is doing the least-bad thing if you take as axiomatic that you're going to have to store your mail in plaintext on the servers of some enormous American corporation. There are, of course, alternatives that don't involve storing your emails in this way, which is the entire point.
For example, libraries regularly delete library records after a short time as a matter of policy. Mozilla encrypts Sync data with a key known only to the user. These represent alternative approaches that don't have the risks of the corresponding Google services (search and Chrome respectively).
if you actually want others to be able to read your email, it can't be encrypted at some point. PGP et al lost the battle a long time ago, which is pretty much exactly the point here. This isn't just in the US that this is problematic, by the way. Most governments reserve this kind of right for "law enforcement" purposes. For instance:
If you want absolute security, you are not gonna get it from nobody, and that includes Microsoft. Any information stored on a server you don't own is not secure, any information passed trough the internet unencrypted is also not secure. If you want absolute security you need to make sure that the information that you want to send is encrypted when transferring and only gets decoded and stored on servers you own and know to be safe from anyone, in other words, don't use email at all, because it's not secure by design, most of the time, it's vulnerable to man in the middle attacks.
Shame on Microsoft for not competing with features instead of FUD.