You couldn't possibly argue that Gmail is the superior solution if privacy is a legitimate concern for you. It has nothing to do with being a blind Apple fanboy, it's simply a matter of fact: Google's primary business model is selling ads targeted to you based on the personal information they collect about you, whether that's through social media, your browsing/search history, your emails, etc.
Whether iCloud is the overall "better" mail service is irrelevant; if you value privacy, Gmail isn't for you.
Make no mistake I'm not advocating for Google.
Nor am I attacking Apple.
I've been a customer for years before iOS even existed.
The topic is best email, if you scan the blogosphere you'll noticed Gmail is the choice worldwide. It's well known as the best email solution.
Now let's talk privacy. Since day one Google's business model is all about selling ads. That is no secret. Nor is it the dangerous nefarious business the paranoid individuals choose to fear. They can only collect what one gives them.
Apple on the other hand has every users full legal name, address, phone number, and complete credit card information_On_File! That leaves Apple in a supremely powerful position. Further reinforced by the fact that Apple Pay will be an immediate easy success for them.
Now let's talk business... And everything in the world revolves around the business of extracting as much money from customers as possible. This cannot be denied. Or if one does choose to deny it they're only lying to themselves.
Finally what's commonly overlooked is Big_Data. They already have everything on us!
Far more than Apple, Microsoft and Google combined. Fed by insurance companies and now the advent of electronic medical records which Apple is targeted with its health app and real time tracking via Apple Watch, suddenly Google is looking like a novice.
Bottom line on privacy?
That horse left the barn a long time ago.