I've been using DudaMobile.com for several years.
Until the last couple of years, I maintained a free account for the most part.
However, when I built my FixMyComputer.Today website, I chose to try Duda's new platform instead of Mobirise or some other option (other site builders I have, a templated site requiring modification or whatever).
It was very easy and inexpensive, even with SSL included in my paid option for that site.
I've tested on several devices from large screen TVs, various monitor sizes, 15 and 17 inch laptops, a 10" tablet, and cell phones as small as 320px by 480 px in both portrait and landscape mode and have had no issues to report in my testing.
I would highly recommend them if you want a fast, easy way to build a site that is compatible, display-wise, with pretty much all devices.