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I don't consider myself an expert on IDX & listing integration, but I'd personally choose a Wordpress-based site with a reputable real estate agent theme. I'd choose Wordpress because it will be a lot easier to add additional content than most custom CMS options (and I'm biased towards Wordpress in general). A couple I've heard of (can't vouch for any one in particular): https://placester.com/ http://themes.agentevolution.com/ http://www.wp-agent.com/ http://www.premiumwp.com/the-best-real-estate-wordpress-themes/ seems to have a good list as well and updated recently. Also, you could try Googling competitive markets (e.g. Chicago real estate agent, New York real estate agent, etc) and open up the top 10 results, and see which ones are based in Wordpress. If they're ranking in those SERPs, it's a good sign that the SEO aspects of the site are working just fine.