As a fan in their mid-20's, for me it's definitely Jack Grealish.
Previously I would have given Laursen the nod, but the way Jack came in, at our darkest hour, as captain and led us to promotion is truly the stuff of folklore. You really couldn't have written it better.
We've had great players in my lifetime who I've loved watching (Laursen, Mellberg, Carew, Young, Milner, Gabby), but ultimately Jack went one better than the lot of them by helping us win something, and achieve a tangible outcome that will live long in the memory.
For me it's one of the reasons that he's so important to the club - he's an absolute icon to an entire generation of young fans; and he stands pretty much alone.