My strategy is to fill up the addon boxes as soon as possible and then upgrade the selected weapons. Whichever come first. I leave an empty slot the laser as it feels like the most powerful one and it's a priority. So sometimes I select common over rare. Not sure that's the best strategy though.
Meet you on the battleground and thank you!

You asking my opinion really feels awesome as I think generally you and Chiller are the pros, unbeatable!