4 is the best because it blends the timed run into free skate perfectly.

Tony Hawk's Underground is the best in the franchise because you can get off your board for positioning which is a critical common aspect of Skateboarding.

The forced timer makes the other games unplayable once you have done away with it.
I cannot be refuted because any argument made will be made under the false pretense that Tony Hawk's Underground isn't the best in the franchise, which is an inherently wrong opinion, making you factually wrong.