I own a small corporate housing company. We provide fully furnished apartments for rent on a daily, weekly, monthly basis. Currently using Airbnb, Booking and Craigslist ads to find guests/ tenants. How do I research which way is best to reach out to people?
Frankly, you are advertising in the wrong channel. You say you're in Corporate Housing but you have all your marketing spend in consumer. You must be putting most of those dollars where corporations go to find weekly or monthly rentals. That is not where you are now, and certainly you should not be spending much on Facebook for prospecting. Corporations simply do not go to those sites to find what you're selling.
You don't say where you are located, so I cannot get very specific. To find where you need to be, Google "corporate housing" and "corporate apartments." I'm guessing the Top 10 listed (not advertised) returns will be your best choices. If there are none, then Google / Bing advertising may be an opportunity.
The biggest directory in Atlanta, and across much of the US, is ApartmentGuide.com that provides both renters and corporate apartment listings. There is also the Corporate Housing Providers Association that many providers belong to: www.chpaonline.org. Similar listings and associations will be available in other countries.
You should also be optimizing your website for searches that are localized, such as "corporate rentals Toronto." Of course, local networking is also important to make connections with companies that may need your services in the future; business cards still have "stickiness."