Earlier quoted context omitted.
I've never been able to understand why anyone with a clue uses Gmail. I just have all my devices sync to an IMAP server provided by an ISP. Android phones have a perfectly good IMAP client. No ads, reasonably good spam filtering, and reasonably good search capability.
Sorry, I don't understand your reasoning. Why do you trust your ISP more than Google? ISPs have much more shady practices and are able to match your online and real persona with 100% accuracy. If you care about privacy, why do you use Android(non-cyanogen I assume)?
Presumably because the ISP doesn't generate the vast majority of its revenue from targeted ads based on information it collects from them.