I've tried Clozemaster several times and always uninstalled it within a few days despite really wanting to like it. I could happily ignore the bad UI if the functionality were good, but I've found that the pacing lacks structure and a sensible learning curve. You'll straight away be given bizarre sentences with complex grammer which is unsuitable for your level (in my case, beginner to beginner / intermediate depending on what language I've tried). For all Duolingo's faults, the learning curve is at least well suited to beginners - the first few lessons are always very basic and it builds from there. I felt like Clozemaster was only suitable for someone who has already learned the language and simply wants to build vocabulary.
My experience with Lingvist was the opposite. The UI feels polished and the sentences feel natural and comfortable to learn even for a beginner. It's a shame that it's so expensive - I'd quite happily pay $100 or so for a lifetime membership but sadly they don't offer that.
