>>31560614Whirl Islands was horrible. Completely trial and error without a guide, and needing Flash is the icing on the shitcake.
I'm going with BW2 Victory Road. Massive, sprawling, hard as hell, but multiple routes and areas. I'm also really fond of Reflection Cave, it's really pretty and the gimmick that trainers can see you through the reflections was really cool.
Mt Lanakila would have been fantastic if it was longer and there was more to do, the atmosphere was great.