Definitely the best advice to know what tools to use is to know yourself first. Personally I only really learn things when I can completely focus on learning the new information, and when doing that I find pretty much all mobile apps are designed to “waste your time” in simpler easy to do things. When given really easy multiple choice problems its very easy for me to get bored and give up or to not bother learning anything and just start guessing. Duolingo is obviously much much worse at doing this than LingoDeer, and LingoDeer actually does have really good written textbook quality writeups from the bits I’ve looked at. Also, many people would probably prefer that sort of thing if they are doing something else at the same time and can also have their phone out and learn Japanese at the same time. If you try to do something like that with Wanikani or similar programs your accuracy will certainly tank.
I’ve never tried Rocket before, but I’m always suspicious of anything that has a huge marketing budget without a similarly dedicated userbase (See JapanesePod101). My routine is Wanikani + Bunpro + Genki with Kitsun (Basically just Anki cards) for vocab and sentences. I use Kitsun over Anki because it’s too easy to cheat with Anki being able to just click “Know” when you really didn’t know it 100%. Recently I’ve just been focusing only on the grammar with the Genki lessons and skipping over the speaking and writing practices. Genki is definitely not what would want to use if you are trying to have fun or some gamification. Other than some of the reading example sentences that can be entertaining to learn the adventures of Mary and Takeshi, it’s still a textbook to get through.
It’s still useful as learning those things lends itself to building other sentences, etc.