Hey, I like the WAILA Harvestability stuff... XDHarvestability, and all the addons, stick so much useless text below the image...
Like light level... when will I need that, when there's CodeChickenCore?
Effective tool? If you don't know whether stone/ores need a pickaxe, then you shouldn't be playing modded MC!
I just find it overall useful. It helps to confirm what I think about what a certain block is; that's especially useful for stuff that isn't immediately obvious as being one material type or another, like, say, Twilight Forest's Liveroot. Plus WAILA in general is really useful for a lot of machines, and stuff like Barrels.