If you just rely on the news media, you'd be convinced that drinking anything but purified water would kill you. Even though there's a lot of news stories about diet sodas, doesn't mean there's solid evidence they're bad for you [1]. A lot of journals won't even publish articles that have negative results (e.g. do not show a link), so you can't rely on the number of studies backing one way or another.

So, if diet soda isn't bad for you, is a surgary drink worse. Since the difference between the two is sugar vs. artificial sweetener, the question can be changed to "is sugar worse for you than artificial sweeteners". Again you probably won't find any definitive evidence one way or another. The actual settled science would just boil down to whether you're consuming too many calories.

[1] https://www.webmd.com/diet/news/20170505/diet-soda-health-ri...