I an unsure how many areas have this situation to choose from so I am just throwing it out there:
If there is a Renfest site in your area that switches to a haunted house in the fall but has no Renfest activities, do you attend it or go to other nearby Renfests in October?
I'm not a haunted house fan so it would be renfest for me
Mine used to switch to a haunted house years ago...we only did the renfaire there...if there were a renfaire going on at the time, I would choose the other renfaire over the haunted house for sure :)