I am using Firefox with profiles for years (maybe even decade). Run Firefox from command line with -P flag to start profile manager or -p <profile> to run particular profile. Rest is matter of shortcut/custom icons to launch.
I was going to say this. Also I havent used FF profiles in a minute but the dialog that lets you select a profile has a checkbox to auto select that profile or something. If you unselect that it should always prompt you about profile. I wish Firefox would make this UI as easy as it is in Chrome. I refuse to login on Chrome to Google.
I have a bookmark to "about:profiles" on my main toolbar (not my bookmark toolbar, I hide that) in Firefox to launch my Work profile and Personal profile. I never use the commandline "-P" option.
My Work profile has a few key bookmarks and extensions in it, but history and cache are never saved and is not linked to a Sync account.
Proving my point that there's no _good_ UI for managing profiles with Firefox. And no, about:profiles doesn't count. Chrome makes it nice and easy and obvious.