You can't go wrong with what you know from your experience.
If you can think of things that'll cause the answer to change, preface your answer with that you're assuming. An even better answer would provide multiple versions of the answer with different assumptions (i.e., "If X is Y and Z is A, this is right, otherwise that is right").
A lot of times questions that elicit "it depends" answers aren't very good questions to begin with: narrowing down the focus of a question so it actually demands a non-wishy-washy response is a hard thing to do for a lot of people. If you think you can improve the question, you should either by commenting or editing. Otherwise, the question really should be closed.
In terms of other people answering with non-answers, downvote them without pity, or remorse, or fear and if you are so inclined, leave a comment as to why. "It depends" doesn't help anyone. We all know it depends, that's why the question was asked in the first place.