When you hit a certain engineering skill level, you must choose between goblin or gnomish engineering. A lot of people used to ask me what the differences are between the two. I told them you can look at shimmering flats for a perfect example. There is a racetrack there where both types of engineering compete for glory. The gnomish team has a huge unwieldy robot that runs around the track. The goblins have a rocket powered pod racer style cart. If you look closely you can see bits and pieces of their earlier models strewn all over the valley. You can also see the remains of one smashed hundreds of feet up the canyon wall.
Gnomish engineering tends to be more fun and useful in my opinion. They get fun things like net guns, shrink rays, mechanical chickens, and force field belts.
Goblin engineers get rocket helmets, bomb dispensers, suicide bomber gear, massive explosives, and the best jumper cables.
The real reason I chose gnomish engineering over goblin is because while most gnomish engineering items can only be used by gnomish engineers, most of the best goblin engineering items can be used by any kind of engineer. You need a goblin engineer to make the rocket helmet and the best jumper cables (these allow you to resurrect people sometimes). Once they are made, a gnomish engineer can use them.
If you love explosives, goblin is the way to go. Otherwise I highly recommend gnomish.