Here are my thoughts: Duolingo is trying to become a one-size-fits-all language learning app with little to no personalization.
They’ve realized that getting users hooked on their app is key to their bottom line, so they’ve implemented a lot of gamification and simplified many features. It’s fine for beginners or casual learners, but in the long run, I doubt anyone can learn much from using Duolingo. The biggest benefit Duolingo provides, in my opinion, is helping learners get started in their language.
On the other hand, LingQ is based on Steve Kaufmann’s learning method, which in turn is rooted in Stephen Krashen’s input hypothesis.
LingQ trains your brain to get used to your target language and acquire vocabulary using real, authentic content. It makes the process of consuming content in your target language easier and more enjoyable. For example, if a real book written in Japanese looks intimidating, you can import it into LingQ and work through it. Do this enough times, and real books will become accessible. Same goes for listening to podcasts. Read the transcripts and listen enough times using LingQ, look up words, etc. and you’ll eventually be able to enjoy podcasts outside the platform.
It worked for me.
LingQ incorporates streaks and leaderboards as well. It is also highly customizable and doesn’t sell your data.