As an American English-speaker I think my ostensible tribal obligation is to call it a tie at worst and take Sir Isaac’s part by default, but Wikipedia seems to be going out of its way to avoid concluding that Leibniz got there first: I’m curious if Germans have a different view than us in the Empire or it’s former colonies.
It seems a tough case to make that Newton wasn’t the more influential thinker overall, but on Calc I-IV? Lot of claims about stuff that he “decided not to publish”.
In the realm of calculus Leibniz is far more influential - his notation, for instance, is so superior that English mathematicians rejecting it arguably led to the stagnation of the field in England. And of course it is far more prevalent today.
Not quite the same thing, but has quite a few references to Newton contained within the pages. Perhaps enough to mix it up in your memory.