I've wondered about this for a long time; is there a metagame for Brikwars like there is for virtually all other tabletop games? I'm talking in particular about the broad genre of post-medieval settings, as they all seem to be very similar (i.e. modern, sci-fi, etc).
In my Brikwarsing experience, Rockets were god-tier weapons, able to swipe away most of a squad in one shot. As a result, nearly all of my vehicles got at least one put on them somewhere. I haven't had a chance to try out the new cannon weapon, but I expect it to displace the preeminence of rockets.
For infantry, I've found that dispersing/spacing them out over a wide area and in as much cover as possible is the only way to make them viable. Trying to replicate IRL IGA Infiltration Tactics has worked best. Otherwise they just get machine-gunned and exploded too easily. I truly cringe whenever I see a batrep or forum battle where somebody just launches a squad-plate of infantry against a tank or doom mecha as though they had a chance to stop it. IME if you're gonna do that you might as well just take all those infantry off the table, because sending them out like that versus such an opponent is gonna have the same result.
I suppose I'll talk a little more about infantry squads because, to toot my own horn, I think I specialize in them. Squad plates are handy for moving outside of combat, but tend to be a death sentence once in combat. An infantry squad's best strength is its ability to present what I call a multi-dimensional threat. If your dudes are spread way the fuck out, some can go up high and around the threat while a few hold its attention to its front while in cover. This way if a tank, say, suppresses or kills the figs to its front it could find a bazooka dude on the roof beside it looking down, or more infantry approaching its sides prepping to do a close assault maneuver and kill the crew. Let tanks and other such vehicles do their thing as the big threats; infantry are the tool of a thousand cuts.