The content overall was fine, i personally had no problems with the systems we got in Cata and even LFR was fine to some extent.

If i had to choose though, most of the focus would be on the last patch with DS, as rebalancing it would be a great help, together with making dungeons much harder.

Dungeons in 4.0 were amazing, with Blackrock Caverns and Grim Batol being some favorites, and while ZA and ZG were great, the difficulty in 4.3 were disappointing.

And if they wanted to keep in LFR, it would be cool to see it be implemented on Firelands aswell, but only when 4.3 came out, as focus would be moved to DS. Have the feature be as it should have been - a way to interact with older content in the expansion, so you could see what had happened up to this point and get some gear to enter the raid.