We have stayed at both.
1st time stayed in the Springs, was at a slow time so bus loads were not an issue.
Have to say preferred the bus stop for the Grandstand because it is 1st, so can almost guarantee a seat (which is great with 2 youngin's) or at least a spot on the bus. Also is but a 5 min. walk to the CH and HRS, so worked out great for us. A couple of times we went to breakfast at AP and then on to catch the bus at the Springs stop, but ended up going back to GS bus stop because buses were full (mind, this was at Thanksgiving).