Both D20M and GT are good toolkits. GT has a kind of simple-but-elegant design in taking D20M's rules and making them a toolkit for both modern and fantasy genres. Really made me think "geez, it's about time SOMEBODY did ths!"
But for a modern-setting game I think D20M has more info that you'll be able to use.
I also gotta say, I actually like the idea of advanced classes, rather than stripping everything down to a talent tree. Strip things down too much and it blandises character advancement. And the way GT hands out a crapload of a la carte core skills leads to cookie-cutting in a system where some skills are unabashedly better choices than others. The ability to buy a "power" skill like Tumble, Spot, or Diplomacy on a 1-for-1 basis should be a role-defining perk IMO, as much receiving high skill points, hp, or BAB, rather than something everybody can put max ranks in.
But for a modern-setting game I think D20M has more info that you'll be able to use.
I also gotta say, I actually like the idea of advanced classes, rather than stripping everything down to a talent tree. Strip things down too much and it blandises character advancement. And the way GT hands out a crapload of a la carte core skills leads to cookie-cutting in a system where some skills are unabashedly better choices than others. The ability to buy a "power" skill like Tumble, Spot, or Diplomacy on a 1-for-1 basis should be a role-defining perk IMO, as much receiving high skill points, hp, or BAB, rather than something everybody can put max ranks in.
