On what distros/desktop envs is it possible to have the same taskbar on every screen?
I recently installed Linux mint ane was unpleasantly surprised that it is virtually impossible on every desktop environment, as opposed to Ubuntu on which it required very little.
You just add a panel to every screen as it doesn't do it automatically, but if you want a taskbar where the open apps are visible from different monitors on the panel then you could try using kubuntu backports for kde 5 on mint, go with the minimal install. You still need to manually add the panel to extra monitors, but they are linked together.
When you add the main panel on a different screen it saves the app layout exactly, don't remember if it keeps clock the same, but you can add that yourself.
I prefer how cinnamons window manger works better, but kde is awesome so I switched.