I chose mobility.
One of the biggest limiting factors in the game is the amount of time it takes to get from point A to point B. This factor limits the opportunities you can capitalize on, as well as you ability to react to those opportunities.
So you have two options to maximize efficiency when dealing with these opportunities.
Git Gud or Git Fast

BUT HEY Predicting player movements with limited visual information and sketchy communication is tough! Mistakes will and can be made! Murphies Law.
Enemy moves to respond to another attack, time to move some drillers-Smuggler
Woah, that guy is going for my squishy vulnerable butt-Smuggler (martyr and Double Agent if your cool)
Oh, jeez im behind and need to make a mine fast- Smuggler
Ooh...Upgrade my specialist and win a fight or- Smuggler
Get Smuggler everytime
