I would like to start things off by simply saying I think I can speak for just about everyone when I say, "I miss custom biomes and terrain!" As a builder, I love to integrate my builds into the terrain rather then generate something artificial, not to mention a lot of my builds are inspired by the terrain I build in. That being said, I don't mean to say that vanilla terrain can't be awesome too, but let's be honest... the custom biomes and trees we had before the May reset were outstanding!...
Custom Biomes
Custom Biomes