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It also depends on native language. In German ground floor is "Erdgeschoß" (earth floor more or less), first floor / American second floor is "1. Obergeschoß" (~first upper floor).

(can also be "1. Stock" (~first floor), very common especially in spoken language since it's shorter, but it also wouldnt make sense if the "1. Obergeschoß" was the "2. Stock" so obviously "1. Obergeschoß" = "1. Stock")

So for me the British system makes much more sense since it makes more sense in German and I grew up with German.