Japanese seems easy if you consider just the spoken form (tons of homophones though).
But moon runes, especially Kanji, are a nightmare. IMO totally not worth it just for a hobby.
Learn languages which are close to your own. For example, English came naturally to me not only because it's everywhere and I kinda had to learn it to consume the things I wanted on the internet, but also because it's fairly close to Portuguese. If you change some sufixes to their equivalents in the other languages you already get a shitload of vocabulary, for example most shit ending in "on" in English is pretty much the same in Portuguese but ending in "ão".
As for German, I'm sick of it. I plan on going through a long detoxification period only exposing myself to English, because right now, when I try to speak English, German words come nonstop and I end up speaking something in German. This absolutely sucks for my future plans.