While I can't speak to Babbel's specific features, it seems designed to be easily digestible and "fun". Which is perfectly fine depending on your goals. But I prefer to be efficient with my time. Especially if you are learning multiple languages at a time, it can be difficult to make progress due to overall less time available per language.
In terms of apps, I only use a flashcard application (Anki). I actually started learning Spanish myself around two years ago from no prior exposure. I started with premade decks with the most frequent words and verb conjugations and now continually add new vocabulary as I encounter it. This is all free. Though it takes a bit of time to become familiar with everything Anki offers, the spaced repetition system helps you memorize words more effectively than traditional methods.
I use it to remember things I have learned in all languages I am learning / using apart from other subjects as well. It has become an invaluable tool for me in almost all my learning. The only downside is that it can feel tedious at times.
Given the time investment during those two years, I am very happy with my current level of comprehension of Spanish. Anki additionally gives you complete control over your learning data, which is a huge plus. You can create your own decks or use community-created ones, making it very flexible.
If you are interested, I could even link to the specific decks I used in my learning process. From my understanding, Memrise is also based on a flashcard system, so the concept should not be entirely novel to you.