That’s quite the contention and an awesome title to bait those into a thread, but “The greatest video protagonist?”
I don’t think it’s even possible to choose just one. Arther IS one of the best and he definitely benefitted from a lengthy, but superb narrative.
Personally, I still believe Dutch was the best portrayed character and most consistent out of all the outlaws.
As for best protagonist I’d nominate Kratos, Lara Croft, Trevor (GTA V), Solid Snake, Big Boss, Mario, Link, and Geralt. They come to mind the most by far.