It depends on what kind of promotion is needed. For the search engines, I think there is no difference.
Unfortunately, both domains are unlikely to get type-in traffic, nor name recognition. So, outside search engine promotion, this is really a choice between bad and worse. If other than search engine promotion is required, maybe you can rethink and come up with an alternative domain, preferably word.com, or otherwise wordword.com?
My advice would mostly depend upon the end application/use of the domain.
Pure online activity? Any version but there will be a traffic drain to the .com without the hyphen just by virtue of human nature. "What was that website name? Ummmm . . . exampleexample.com wasn't it?"
For a more longstanding business with an actual address, phone number, etc. where traffic will come from a number of sources? Find a straight .com.
I have always opted to leave off the dash if at all possible. It DOES help search engines identify your words easier, but most claim that having a keyword in the domain only helps you out a tiny bit, and most modern algorithms can distinguish wordword pretty easily without a dash.
Also for word of mouth advertising (which is not always just verbal) there is a big awkward confusion that the dash creates. You website will not be wordword.com it'll be "word dash word dot com". Just keep it in mind.
That's just my own thinking and experience, I'm by no means an expert.
My largest site (so far) is not a .com and it has a dash. Traffic is pretty good.
I think it all depends on what the content of your site is, compared to what the content of the non-dash (and .com) sites are. If someone who mistakenly types in the non-dash (or .com) URL is confused and thinks that possibly they've found the right place, that's a problem. If they instantly know that they must keep looking, it's not so bad. I think that's the case with my site, anyway.