Make sure you don't debate too long and the domain(s) get registered in the meantime. At the end of the day, it's about a $7 x 2 for you to get both which isn't that bad. Then you can test each of the names to see which your end users will prefer. Can run a poll on the website or something like that. Do that and save your time, and money.
Even though this is an old topic, I really like your answer. There is some truth in it. Who knows, maybe search engines really are secretly fans of those dashes!
As mentioned above, If the domain is for commercial use, go for the .com. Even if it has the "-". The .com is the one I would choose.