There's two questions:
How come one is still open, and the other one closed? I ask because both seem to me to be mere curiosity questions.
Because worst software bug can, in fact, be measured -- how much damage did the bug cause in billions of dollars? How many children were killed by this bug? Did the company go out of business because of it?
Whereas favorite programming language -- how exactly do you measure a favorite? This is just "what's your favorite color?" in pure form.
If you can't see the difference, you're not looking hard enough. Try harder.
Check out this 'discussion' or lack there-of.
It's pretty clear that 'favorite' is one of those keywords that doesn't hit the filter (least favorite or most favorite doesn't matter)
My suggestion would be to either take your chances and use the queen's english "favourite" (which according to my Fedora Spin, is in fact the correct spelling) or just replace the word with "Won the most awards" or "Killed the most people"