Having tried most things so far, terraforming by far gives the most xp. I can gain a full level in a just an hour or few of gameplay. The same time in another craft (like toolcrafting) is a day or two.

I am guessing that since it never fails, it always registers as a positive and you gain really fast. I could see macro-ers just terraforming down and up on an area and leveling very quickly. I put it as a priority 3, because if macro-ers do this, the system for level design will be out of whack with the macro-ers having huge advantages due to skill levels.

I think the ratio needs to be reduced drastically like 1/20 and make it time based, so no more then X (or X%) xp in X time no matter what you do.