I'm an entrepreneur who uses PromoRepublic* to schedule my social media posts of my website - MandieM.com, and I'd love to share my thoughts on it!
It analyzes your audience to help you choose when to post. It also gives suggestions of what types of content to post, like blog posts, informative pieces, entertaining pieces, and when you should go in for the sale with a promotional post.
Additionally, it offers a ton of images and an in-software editing piece that allows you to either choose pre-existing templates and edit them to personalize the content to your site, or plenty of components you can combine for beautiful graphics. It suggests other blog posts and articles, too, if you want to intersperse other content with your own. You can use it for just about every platform, including groups on facebook.
The only reasons it isn't a solid five are that it alerts you to post on Instagram instead of doing so directly (which I know is because of Instagram's agreement and not because of PromoRepublic), and because it doesn't do as well with multiple images or videos - some of that must be done manually.