Elizabeth I. Look at the country she inherited: A bunch of people scared because the religion of 'choice' changed from reign to reign. A bankrupt (just about from what I remember) treasury. Not a lot of respect from the other countries (well, until that whole Spanish Armada thing

Elizabeth was the one who really stopped the going back and forth between religions. She also was actually quite tolerant - as long as you went to church, she didn't much care what you believed.
She was VERY shrewd, politically. By courting all of Europe for her entire reign, she kept a lot of countries as friends. By not naming a successor she kept people from trying to kick her off the throne (but after Mary's rule, I don't think anyone would have). She even kept Mary, Queen of Scots around as long as possible, until she actually became a huge liability...