One thing I hate is that the go flags package sorts the options by default. Ordering options in a thoughtful way is definitely a plus in an api. I know there are (not very intuitive) ways to override this, but I just can't understand why they would make such a bizarre choice even given their penchant for being opinionated.

edit: Now that I read this over, this complaint seems a bit misplaced in this thread, but I guess I'll leave it due to its sort of relation to cli programs in go.