I've been paying for my Gmail access for a couple of years now, in the form of a Google Apps account, works great. Part of me want to self-host, but the gmail.com client and their spam filters and priority inbox (good for removing marketing mails etc) keeps me 100% happy.
My self-hosted email was insecure (no SSL), noisy (no spam filtering), and occasionally difficult to use (I didn't set up a web interface, only IMAP). Furthermore, I've lost email due to my own incompetence/corner-cutting, such as bad distribution upgrades and failing to properly restart postfix. These are all things that I could solve, but that's also not free - it takes a large portion of my dwindling free time.
I also have a Nexus 4 and a Nexus 7 - the integration with other Google products on these devices is the lowest friction route to a very enjoyable experience.
I'm not happy with the amount of data Google have about me, but I'm happier with that than losing my free time and having a second job just to manage my own shit.