Okay, Boba Fett would have a really good chance against Grievous. He has a jetpack with a missile on it, he's got all sort of gadgetry and what-have-you's on his suit and he's incredibly skilled with his weapons of choice.
General Grievous on the other hand, is a tactical genius, and an expert in lightsaber combat. Not to mention his incredible ability to kill Jedi with or without sabers.
Based on their tactical knowledge, weapon choices and skills with those weapons, I will stick with General Grievous. He knows how to get a job done.