Depends what you want, i think you'll find more reliability out of the Skyline, If you're looking at spending say 18-20,000 then i'd definately look at a skyline. Like all cars though, shop around and wait for that car you want. Try and drive both, but use your head to, cause if you go for a trash around in a GTiR you're gunna love it, they're a really fun, quick car.
But you're definately asking the wrong crowd, (almost) everyone here bought a skyline for a reason...