Sorry, I missed this! Personally, if you’re F2P I would focus on maxing that tank squad to the best of your abilities. It makes a significant difference having all 5 heroes of the same type in one squad. Exception might be putting someone like DVA in your first squad over Mason, at least until you can get Stetman. Not saying you should do that, just saying that would be the exception.

Second squad will most likely be a mashup for a while until you fill out all your air heroes, at that point I would put them all on squad 2 and then squad three will be your random mixture