GitHub pages is, hands down, the best place to start if you're still looking for a place to host your first Jekyll site.
GitHub pages is even a great long term solution since they support the most popular Jekyll plugins and you can publish your site directly from a GitHub repository, meaning you can publish unlimited sites... for free!
You can even use a custom domain and GitHub issues you a free SSL certificate.
Having an easy content management and hosting solution is key to a successful Jekyll site. Waht's more is that a bad or slow hosting provider can make or break a visitor's choice to stay on your site.
GitHub Pages is a great starting point because it's free and it's even a great long-term solution as GitHub allows you to host an unlimited number of GitHub Pages websites right from your repositories. But services such as CloudCannon, Forestry, Netlify, or Siteleaf are also great more advanced users.