I think redraft is a great format for people who love football, and want to do something that's strictly about the football. Loving football is both necessary and sufficient for enjoying redraft leagues. This is not intended as a shot at redraft leagues- I love football, and therefore I love redraft.
Dynasty is a different beast; it's not just about loving football. Obviously loving football is still a sine qua non, it's absolutely necessary... but it's no longer sufficient in and of itself. In order to love dynasty, I think you also have to love strategy and game theory, as well. I think the chess comparison is an apt one. In redraft, all "strategy" really just boils down to "get the best players, win". Any unsettled strategy decisions remaining in the format (e.g. when to spend blind bidding waiver bucks) account for just a small percentage of success. In dynasty, though, the unsettled strategy decisions account for EVERYTHING. You have to devote a lot of time just to the concept of understanding what "best" really means. How should current production be factored against future production when determining the "best"? How do you weight value over a short timeframe vs. value over a large timeframe? How much risk are you willing to accept, and how much value are you willing to sacrifice to mitigate that risk? In redraft, there's a lot of material out there for you that will easily and clearly spell out what "best" means, meaning you can get by with as little effort as you really want to put in. In dynasty, there are a lot of different theories about what "best" means out there, but there's no way to tell which theories are more credible, or even if any of the theories is the best fit for your team. You have to do a lot more legwork and rely on your own opinions a lot more. Your team becomes much more a reflection of your own personal beliefs and biases than it does in redraft. This also means that the teams you're competing against are going to be much more varied and eclectic than anything you'd ever face in a redraft league. In redraft, the number of possible variables and iterations is low enough that "strategy" is very simple with very little variety from team to team. It's not quite tic-tac-toe, but there are really only one or two successful philosophies for building a redraft team. Any disagreement comes down strictly to disagreement over projections rather than huge strategic conflicts. Dynasty is just the opposite- all sorts of theories and worldviews will enter the arena and battle for dominance.
I think dynasty appeals to me most because that aspect of it is right in my wheelhouse. I'm what's known in the gaming community as a "min-maxer" or "optimizer" or "powergamer" (or, more derisively, a "munchkin"), someone who is always looking to tweak around the edges to perfectly optimize and streamline my approach. I spend a huge portion of my time considering meta-analysis, and I love Dynasty because the format actually rewards my efforts and allows me to use that to my advantage. Rather than play in a format where the huge strategic questions have been settled for over a decade now (ever since the advent of the concept of VBD), I'd play in a format where those questions are far from settled, and someone who is able to do the legwork and get ahead of the strategy curve can leverage that advantage into tangible, demonstrable results.