Best App for language learning

I don't want to start a flame war. But I do want to ask people to compare and contrast the different apps available for languages. Not too long ago I did a review of Clozemaster after someone did a full thoughtful review of Duolingo (which I cannot find). I did find a fairly negative thread about Duolingo(disclaimer, I have never used Duolingo). I know there are other apps Anki, Tandem, HelloChinese, etc. I was wondering about a compare and contrast thread.