"I've heard lots of horror stories about U.S trucks, but Toyota and Nissan seem way overpriced."
Correct me if I'm wrong, but you already own and are driving an American "horror story" in the "American named" Chevy Colorado / GMC Canyon pick up in the Isuzu. They share the same platform.
If you need a full size pick up, I suggest you buy one on it's own merits whether it be "foreign or not". They all have their advantages but all like gas more than the intermediates. In full size my first choice would be the F150 and second the Tundra.
No one builds a better compact truck IMO than the Toyota Tacoma with the 4.0L motor. It can handle heavy loads much better than the Isuzu/GMC you have and do it more economically. A half ton is a half ton whether it be compact or full size. Toyota Tacomas are more expensive because of their higher demand and capabilities. Crawl underneath and look and compare; compare performance of their motors and check long term reliability. The Chevy Colorado is POOR according to CR and the 2.9 is weak. That's why the Isuzu cost less than the Toyota Tacoma. In this case, you get what you pay for. The F150 will cost more than Isuzu compact for the same reasons.
I also agree with "Same" in that where you live and the business you are in may ultimately limit your choices.