Prepared/static strategies are something that are interesting to people? I dunno about you, but when I was first learning TF2, I DID find gravelpit/AD in general fun. However, as time passes on, you start to realise the myriad of different situations that arise in push and koth maps. Showcasing how well you can adapt in these different situations - that I believe is where the true beauty in competitive TF2 is.
Anyway a sneaky bit of a segue in response to ma3la's post - I'll go on-topic now. If you are going to keep some form of granary; definitely pro granary is an upgrade. I still feel that it's a pain in the ass to defend 2nd if you lost mid p horribly, but that's not gunna change unless the 2nd is opened like crazy, ruining the play of the map.