If a domain will give you real SEO benefits,it'll need to have any or all of: direct search traffic, existing traffic from websites they've powered before, a nice amount of healthy backlinks, be dense with keywords people search often, and very IMPORTANT - not be penalized by Google.
When evaluating an expired domain, use any of the popular SEO tools to check the other metrics and also see the domain's traffic history.
To confirm that it's not being penalized, go to Google and run this search:
site:yourdomain.com
If the site has very few or zero pages indexed compared to how man pages are actually on the site, that's a red flag (not certain though) for a penalty or deindexing.