I second @owel’s recommendation for WP. It’s my personal go to for client sites, even one pagers. Granted I usually build my own themes from scratch and then I’ll utilize posts for various text content and images. But, if you get a good grasp on how to loop through posts, categories, and tags you can set up your own editable sections within any theme. Heck you can make them with widgets too if you want to get extra crafty.
I guess it really depends on how often your client needs a.) updated content and b.) how much updating needs to be done. If it’s pretty regularly, I think a CMS is the way to go then. If it’s every once in a great while, well I’d still recommend a CMS–especially If you want to remain hands off when you’re finished with the project.
The worst thing you want is for them to have to get into the code when they have never touched it before. While you might not miss something as simple as a missing quote or an end tag or a semicolon, they totally might and break the entire website.