Favourite and least favourite skills to build?

Everyone mentioning logic as least favorite, do not forget about the telescope as a way to raise it. It's pretty fun, gets you some very nice prints for hanging on the wall that have great Focus-granting auras (power level 7) and look fantastic (assuming you like cool pictures of the sky, which I do).

I tested shrinking the telescope down using the [ key and it still functions when shrunk way down...animations are a little wonky though.