Mah-rio, hell even the games says it this way.
The way how he pronounces it. Who would even pronounce it as May-rio or Mair-io?
It's very rare that I hear someone say "May-rio", but every single time I've heard it, I've felt extremely uncomfortable.
It's like when someone says "Jif" instead of "gif".
The G stands for Graphic, not Jraffic.