I use a few different distros on a routine basis. Out of those, Ubuntu would probably be the best fit - it generally works right out of the box, the UI is intuitive for day-to-day use, there's plenty of information online about how to install/use/troubleshoot it, and the App center has an open source alternative for anything and everything. Mint might also be a good fit - I had a very positive experience last time I used it, but that was a few years ago so I haven't tried the newer releases.