Our favorites for race weekends have been Poly and BWI. As a runner, I like the Epcot area resorts for the reasons others mentioned. I haven't ever gone back through Epcot after any race, but I like to have Epcot nearby. I also like the variety of restaurants for pre- and post-race meals in the Epcot resort area and Epcot itself. And I tend to do a ton of post-race walking (which I enjoy) when staying in the Epcot area.
On the other hand, we find there is a huge spectator advantage when staying on the monorail. They can see me run by at TTC, Poly, and possibly the Epcot lot before heading to the Epcot finish. And they can do it all by foot and monorail, so no worries about traffic, etc. When we've stayed at BWI, my family has missed me at many planned spots because it's often hard to get around - they have used both Disney transport and cabs/uber. Just too many variables with both. And as much as I will tell my husband not to worry about it and just meet me at the finish, he insists! So I want to make it easier for him.
We're at GF next weekend, and while I'd love to be closer to Epcot, I'm happy knowing how easy it will be for my family to spectate!