What domain name should I use?

You would be filtering the traffic. the people who write the .com will end up in the parked domain instead of yours. They may even think that the site you build on the domain is no longer there and that they will never try to visit it again.

Also, what happens if the domain is sold and the new owner places a site in the domain? What happens if the current owner decides to build a site on it?

It is a risk, but if you are not worried about that, then use the one that you like the most and that you think will be your best option than what is available for your needs.

As I said before, if most of your traffic comes from links that people click on in search results or from other locations, then it will not matter as much as if you were expecting, for the most part, to enter traffic.