- Google has already its hands on so many things. If I can prevent it from controlling my browser, I'm good.
- I HATE chrome UI and look & feel
- With FF, I can syn my tabs between several devices while hosting my own sync service .
- Google is not beyond Firefox. I like more Mozilla than Google.
A late reply but I thought I'd chime in.
You also need to host your own accounts service and all its dependencies (assets, tokenserver, profile), unless you trust Mozilla to be not forced/coerced to compromise your security. Even with auto-updates disabled, the Firefox Accounts login form is served from the network, so a paranoid user must be very cautious if any of their browsers suddenly asks to re-authenticate.
Also, note that Sync is now consists of two pieces: there is Sync 1.5 server and there is Kinto (which is used to store WebExtensions data). This is usually not mentioned in the "host your own Sync 1.5 server" articles, but here are the details: https://wiki.mozilla.org/CloudServices/Sync/ExtensionStorage...
If you're fully self-hosting you need to install the latter as your tokens aren't working for Mozilla's one (so basically your WE-based extensions can't sync anything). If you're only hosting your own Sync but not Accounts, you should be aware that some of your data is stored at Mozilla's services instead of your own server.