Each user has it's own cookies, chrome extensions etc. Keeps work and personal accounts very separate.
If you start firefox with the "-P" flag you can choose to create a new profile. You can also pass it an argument (e.g. firefox -P default) to choose one.
In this case, the profiles are completely disparate; there is zero overlap. In this case, you simply have to login to one google account per window and paste into the correct window (still not ideal).
To run multiple profiles at once, launch all profiles after the first one with "firefox --no-remote -P <profile-name>". Clicking links will open them with the firefox that was launched without "--no-remote".
For example, one of my main uses of multiple-profiles is that I have a different profile for every proxy I use. I can launch a firefox profile that's proxied side-by-side with my usual firefox (aside, the firefox proxy settings are exposed via the UI, unlike chrome).
Chrome, I'd have to run "google-chrome-stable --proxy-server=$proxy" and then, again unless I'm mistaken, all accounts will use that proxy server. That, by itself, is a deal breaker.
I'm not familiar enough with chrome's settings and so on to say what does and doesn't leak; I could be completely wrong on all of this, but I suspect I'm correct.
Edit: On looking more, Chrome's does look more complete than I thought. The proxy bit still is a dealbreaker for me (well, and I'm adverse to logging into a google account), but I retract much of what I said.
It's just not as good security and privacy-wise. Using proxies on/off on one profile, as it encourages, results in any tracking cookies seeing both IPs having the same tracking data, and thus your proxy has lost some of its privacy.
I also run entirely different extensions when I'm going for privacy vs fun browsing vs banking etc etc.
If you just want proxies to get around some region restriction and don't really care about the privacy or security aspects, then FoxyProxy might be fine.
Sadly it was very difficult to maintain.
Using OSX, when I click on a link inside Mail, it opens it in Chrome using the last used user. It's annoying when it's the wrong user. You still need to switch users and reopen the link in Chrome.
It also allows for binding certain URLs to specific browsers.
BrowserChooser http://browserchooser.codeplex.com/ is a nice tool (like Choosyosx) to help select what URL to open in which browser.
To sync to Google Drive, I use Syncdocs http://syncdocs.com which is an enhanced Google Drive sync app that enables syncing multiple accounts at the same time.
I think Google wants each user to only have one account, which makes it better for them tracking ads.
I'd recently looked into ways to cure the pain of multiple google drive accounts running on the desktop app. People spoke highly of CloudFuze and InSync, but their support forums were filled with really awful error reports about random file deletions or endless file replication.
These services sound like a syncing layer on top of a syncing layer, which seems prone to errors.
It's a fucking godsend, every computer I have has 3 different Chrome accounts on it, all short cuts on my tool bar.
On windows at least it is trivial, extremely trivial, to switch between them. You will generally be in one of the modes, for me these are "their company", "my company", "personal".
Whichever one you used last will be the one that receives the "open internet" command. So if you are in "their work" mode, reading your emails in their email client it will open the google doc in the right context.
For you your workflow is somehow broken, for me that's exactly what I want. If I'm in "their work" mode, I want all browsers to open in that context. I'm not expecting them to be psychic. That means 95% of the time it just works because you are already in the right context. The other 5% you get used to very quickly. If I open up my personal email account, I want any next links clicked to be opened in that context.
Added bonus, it's great for every SASS not just just google accounts.
Does it? I don't know either way, but if I were google I would link the two accounts (just takes one more cookie at most!) so that if me@work-acct searches for a car, then me@home-acct can be served a car ad....
That said, the OP had 4 google accounts, so I can see how this could get messy.