Welcome to the Forums, @Zonero174!
Alertness can definitely be used to Defend against almost any physical threat; If one can sense something better, one can Defend against it better. Generally in SCRPG, if you can fictionally justify it in the narrative, you can do it.
If you’re talking about mechanical usefulness, pretty much all the Powers and Qualities don’t really have any mechanical differences. It’s all about how you use it in the narrative.
If you’re interested in mechanical comparisons of Powers, Qualities, and other things, I recommend . . .