Biased toward this one because even though it's not the first Souls game I played, it's the first one that grabbed me enough that I played it to the end. Not knowing what to expect and being surprised by awesome and interesting shit around every corner is one of the best gaming experiences I've ever had, and cemented FromSoft as one of my favorite developers. In retrospect it has a lot of issues, is really linear and over reliant on DS1 throwbacks but still great nonetheless. Wish I could relive that first playthrough though.