I would recommend just going to a site like themeforest.net and buying a theme you like. I did that, searched for “bootstrap 4” under their landing page, and quickly built a site that would look better than anything I could ever do.
We from https://saasmark.com are aiming to solve this exact problem. We are currently in Y Combinator Startup School and are launching our beta in a couple of weeks. In case you are interested to check our service and give us some useful feedback, please let us know.