Agree 100%. I am not sure why some would point to the controller(s) and some would point to HSRP devices upstream. It should be all one way or the other. There are no features you would lose by having the traffic use upstream devices as their default gateway. The controller still "sees" all the traffic and can allow/deny/queue it correctly.
I would say point them all at the upstream devices. That will eliminate the possibility that an AP is on one controller and the VIP is owned by the other. That situation SHOULDNT happen, but you never know. Traffic would still get to the VIP, but it would sub-optimal.