Looking for solid ways to deal with Annie Mid

Up until recently I didn't encounter many Annie players in the mid lane, which is weird since she's got such a high win rate and a fairly high pick rate in lower elo. The few I did come across must have been playing her for the first time because I did a pretty good job stomping them each game I did come across them.

Long story short, I'm looking to find solid counters for Annie. I find that Xerath works fairly well because you're never in range for her to burst you, but I could use some better alternatives as well.

I think what I'm looking for most of all is an explanation as to why whatever champion you'd chose would in fact be a counter so I can understand what part of them is the counter, like for Xerath with his range.

I appreciate the help.