While no system is perfect, I do think that GURPS has some significant advantages. Recently, we just wrapped up a Deadlands campaign. We took Deadlands, Deadlands d20, and GURPS Deadlands and compared them and we came to the following conclusion:
GURPS encourages tactical thinking because it's damn deadly.
In Deadlands, a shot to the head from a .45 caliber pistol averages TWO wounds to a normal human (average 17.5 damage, divided by a 6 size). That means it takes an average of three head shots with a Colt peacemaker to drop someone. That doesn't exactly make for very scary gun duels at high noon.
In Deadlands d20, it gets even more ridiculous because of the hit point mechanic. It's a wonder anyone ever dies when a competent gunslinger has 5d10 hit points. It's not the wild west. It's Hong Kong Action, where shotgun blasts to the chest are minor inconveniences.
In GURPS Deadlands, you get shot in the head with a .45, chances are very, very good that you will *die.* Or at the very least get knocked into a coma.
This is just an example. GURPS encourages more realistic combat. A swordfight is a mobile series of attacks, parries, and dodges, usually until a single solid blow lands and someone gets crippled or killed. None of this silly hit point contest stuff. And so on.