Worldbuilding, plot, and magic systems are great--but what's more important to me when starting a new series/book is whether or not I care about the main character. I normally prefer the story to be engaging right from the start as well.
So, if I begin reading a work for the first time, I'd like to get to know a bit about the main character first. If I start to care about the character, then, I would get invested in the plot, followed by the worldbuilding and magic system. Of course, I'd want the character to succeed and grow as a person (personality, character development, power, etc.). But if I don't like the main character, then I won't care about the plot or any of the other things.