To be clear, I can work in any content management system. I've built sites in ExpressionEngine, Drupal, Wordpress and more. I prefer Craft CMS because it's it starts with zero assumptions about what you're trying to accomplish.

1. No themes, no starter templates, no cruft. I'm a designer and a programmer – I want to start with clean slate.
2. Just enough plugins to get the job done. The majority of what you need to do in a CMS is already built in to Craft. But where the bases are not covered, there's a plugin to get the job done. There may only be one or two plugins that address your special need, but to me it's preferable to weeding through 1,000 plugins that do the same thing in varying degrees of success or failure. Wordpress currently has more than 54,808 plugins – who in the &$!#% has the time for that!? 😜
3. It's not free, but it's not expensive. In general, I'm a "free is good" kinda guy. But if you're a company that needs quality, $299 ($59/year after) for an awesome CMS is not a ton of money to spend. Besides, when money comes into play so does accountability. You want accountable developers who care about what they create and are there to answer questions when you need them.
4. Live preview in a real-time split screen as you modify your content in the CMS. The days of having one tab open with your CMS, another tab with your website, and then constantly refreshing the page are over.
5. Step into the Matrix. In a nerdy nutshell, Matrix allows content managers to build pages like they would use Legos. Add a text section, add an image section, add a video section, etc. Then change your mind on the order of these objects. It doesn't matter because Matrix allows you to do any of this and more. This website is built using Neo, Matrix and a ton of code I've written to make things magical.

But you don't need to take my word for it. I urge you explore what others have said about this platform.