For open source and lots of features, try Neko / Nekogram. It’s very good. I personally use Plus though, it is closed source but had more and better features, in my opinion. However, it is only downloadable from Play which means it has to follow Google censorship rules. If that matters to you, go Neko.

I don’t recommend any other. No reason to. There’s nothing better than these 2.

unigram is really slick on windows compared to the official QT app