low upkeep stack?

Straffez runners, queens, kings (If you have them), and straffez fodder are very low upkeep if you can afford the minerals. Both can be used in any sort of stack greatly decreasing the upkeep cost you`ll be paying. Fodders are generally used more defensively unlike the runners and queens which do well in both cases. I wouldn`t recommend spamming either of the two though, especially runners/queens as they have very low hull. They do work wonders against capital ships though in a balanced stack! :)

You`ll have an easier time studying your ships a bit, than interpreting what other people will tell you about this subject here.

I can tell you what the ratios for pr/upkeep are for every single ship in the game that players can use, from there you`ll have to ask someone else about their offensive and defensive viability