In case you’re unsure of which spelling you should choose, the correct answer is the word without the hyphen. In American English, we don’t hyphenate prefixes (except in a case like re-create [to make anew], which has a hyphenated prefix because it would otherwise be confused with the very different recreate [to take part in an activity for relaxation and fun]).
That said, I agree that there are times when prefixed words look like a jumble of confusing letters. At which point, I might actually say that, to help a reader achieve swift comprehension, hyphenating the prefix wouldn’t kill our language. As an editor, I’m a champion of the rules, but I’m also a champion of clarity, and that’s where some gray can certainly seep in.
In the big picture, though, if you want to use the right spelling and see whether a prefix should be followed by a hyphen, consult a reputable dictionary. And be sure to use the actual big book of words instead of relying on spell check or random online resources—they won’t always steer you in the right direction.