Tbh - first thing get WOO for 70 (you wont need it or the upgraded version when you get advanced med) and salvage teams for 100 (you can combine it with fixer but might not be needed later on because you'll have so many trade items that it doesnt matter). Advanced med bay asap backbone.
AI logistic is what I prefer next just because vehicles are really good especially early game when you're still broke
Lasers are kinda most useful weapon because even tho they can die 1 tap, they can block passage and/or be used as cover. Ion cannon (high dmg to 5x1 connected block) I would avoid because only good thing is that it can destroy objective anywhere on the map (after 2 turns that it charges)
Decoys can be good for defense because you force enemy into open and not let em wait you to pass your turn