I went with Innovative Languages, in my case chineseclass101.com (they have one domain for each language, instead of the usual "courses" but it doesn't matter, except if you want to learn multiple languages at once, then you'd pay double)

But just look up comparisons between different providers, maybe try their free or cancelable trials. The most important thing is, I think, having lots of somewhat "natural" dialoge with increasingly more and difficult vocabulary and you NEED those lessons where someone explains why words or grammar is used in a certain way, which Duolingo completely lacks. Sure, you can get it right by context and a lot of repetitions but this will take many more times than "immersing" yourself WITH some sort of guidance.

If you got the basics down and are at an A2-ish level, I would start watching and listening to a lot in your target language (Netflix, bilibili, podcasts), at this point you don't really need more grammar lessons, just some refreshers, which you get from context, and soaking up vocabulary.