cityhomes.net has a more general, broad allure to it, I think you can use it for a bigger site with more categories instead of just real estate
The other one sounds specific about real estate, so it depends on what your end goal is (do you only focus exclusively on real estate, or you envision expanding into home staging, lawn mowering, landscaping, etc. too?)
The answer to this question will decide which domain you should choose.
From a SEO perspective, both domains are treated equally by google if the 19 years old one had been un-registered for at least 1 year during these 19 years of "liveliness".
Also, if the niche of this domain's content had changed drastically and / or multiple times over the years it's possible that google have already flagged it as spammy and they won't be ranking it easily / at all, so check the history of its content and see if you detect any changes...
Or, if you're unsure which one will perform better just buy them both if you can afford, and build 2 sites in the exact same niche, using the exact same content (but rewrite it to make it unique, of course), and see which one google likes more and keep using that one
