Enginner, where should i spend my station cash?



So the title said all.

i love the enginner class, his use in a vehicle warfare game like PS 2 is unquestionable but my question is: What is best?
i have 4k station cash from the Alpha Squad package and i want to spend them wisely.
Wha'ts the best prowler main and gunner weapon? and cert?
What's the best lighting main weapon and cert?
i've played a bit of the beta but my work took all of my time so i could not play like i would , a lot of things changed since the last time i logged in the beta.
i've seen that there is no enginner guide in the forum so this topic can be an opportunity for some of you with better experience with this class to explain us the way to WIN!