It's true that Firefox is much more extensible and has way better extensions. Like you, I also hate the download manager in Chrome. However, the single feature that makes me try to use Chrome above anything is it's sync features. They are just too good. Sync happens instantly (in my eyes at least) no matter how many computer I'm using Chrome on, and that's just perfect for my workflow. Also, incognito is much more easy to use than Firefox's version..
Firefox's Sync synchronizes more frequently now than it did a few releases ago. If it doesn't synchronize fast enough for you, power users can always open about:config and fuddle with the services.sync preferences. services.sync.syncInterval is the one controlling the default interval (in milliseconds).
While I'm writing this, I should also point out that browser sync is a great example of how Mozilla and Google take a different approach to solving the same problem. Firefox's sync encrypts all data locally using a cryptographically secure randomly-generated key then uploads it to Mozilla's servers. Chrome's sync, by contrast, only encrypts passwords locally by default, leaving bits like your browsing history unencrypted on Google's servers. Chrome does have an option to encrypt everything, but you have to enable it in the preferences. (Firefox has no option to disable client-side encryption.) Even when you enable client-side encryption in Chrome, your data is encrypted with your Google password. This is less secure than Mozilla's approach because 1) your password likely isn't sufficiently complex or random 2) Google sees your password periodically (e.g. when you log in to Google services), meaning they possess the key to unlock your data. With Firefox Sync, Mozilla never sees your private key, so there is no way for them to see your data. Ever.
Google's business model means they have an inherent interest in your synced/private data. Mozilla has no such interest in it. Therefore, Mozilla locks the door and throws away the key.
