Firefox Password Sync nowadays seems just as secure as LastPass. The only thing it is missing is a password generator. This add-on is very non-intrusive (I personally just use it by right clicking the password field and selecting generate password when I need a new one, then right click and choose "insert previous password" if I need to repeat it). The only improvement I can think of would be that generate password automatically populate any password fields (including repeats for new accounts), but then that could come in the way of the natural simplicity of the add on (I found LastPass would, occasionally, try to populate fields it didn't need to).