Victoria 2, although it runs very slowly on my dated laptop.
Well I recently started playing CK2 due to acquiring the old gods and Legacy of Rome DLC's. Well I've just got 50 hours in it. It also doesn't run too well on my laptop (but not as bad as vicky 2) I've stopped playing EUIV due to waiting for Art of War and because I see Vicky 2 as doing everything EUIV does but 10x better.
First I had ckii, then played euiv nonstop, now back to ckii.
I believe that EUIV is an inherently flawed game due to lucky nations and NIs.