For me, it's more of a question of what's most sustainable. Afaik, soy is planted and harvested in Germany too, but oats are just dime a dozen around here, so I stick to those. Plus, I like the taste a little more compared to soy. Soy yoghurt is vastly superior to oat yoghurt, however. Coconut yoghurt is abysmal except for breakfast yoghurt with fruits and baking 💀
I make my own soy milk with soy beans and the soyajoy! Fresh soy milk is my favorite but I think you need to be someone raised on it or level 10 vegan because it is not sweet at all and is like delicious bean drink.
I never really just drink any plant milk, most of my consumption is as creamer in my coffee. For that purpose oat is superior at this point. Just get a barista blend and it stirs in perfectly.
And I completely avoid almond milk (in the US) mostly because it uses a huge amount of water and for whatever stupid reason we grow almonds in places that don’t get rain.
I am a soy supremacist but it's hard to find unsweetened stuff. I have a sweet tooth but I prefer to keep that to deserts, not everything needs to taste like a lollie.