As you've discovered, there's a wide variety of attic stairs out there. I faced your exact dilemma when I needed to replace a shaky set of attic stairs in my own home last year. The starcase I ultimately chose was the Rainbow Attic Stair. This is a steel product unlike any other I'd ever seen, with a prefab stairwell and an accordion-like stair that unfolds from it. I find it to be very heavy and very sturdy, and I utilize my attic more as a reult. Even more, it's much more efficient than traditional attic stairs.
One tip if you go with Rainbow: You're going to need a couple of strong friends to help lift it into place! Rainbow Attic Stairs are heavy. They're also much more expensive than the tradititional attic staircases you find in home centers. In my opinion, the investment's worth it if you use your attic stairs with any regularity, or if traditional stairs leave you feeling unsafe.
As for your roof trusses, they shouldn't be a problem because attic stairs are designed to fit within the two foot uncenter space. For example, a 22.5'' x 36'' stair is designed to fit exactly in that opening.