There's only a little over an hour before it's done, but holy shit, MGS3 is RE4 is brutal for me. I played the absolute fuck out of both of them as a kid. I've likely played each of them over 3 dozen times. They're games I still go back to every single year. Shit, I was just thinking about doing another playthrough for RE4 the other day.
I ended up voting for RE4. It was hard to choose, but I do think it's very slightly better over MGS3. Because while I would play through MGS3 over and over, I felt compelled to do absolutely everything in RE4. They're both almost perfect, I just think RE4 is closer to perfect.