I feel like the way tech is handled in the game kinda limits it in a way as you get pushed out of infantry battles in human vs human incredibly fast and aliens basically tech to 2 before there's even a chance of you finding their base (I do like the idea of aliens being a rush faction though). I do really favour the humans vs aliens rather than human vs human so heres some tech ideas:
-Aliens can build greater and lesser spawner's off the start but make the units from them have an increased cost based on tech level so that players have options for different and unique openers, for example a scorpion rush; cripple your economy and put your tech behind so you can get a scorpion or 2 out really early and attempt to cripple the human economy or destroy their tech, high risk high reward opener.
-Humans get specific tech upgrades that are cheaper or more expensive depending on what they do, an example of this "heavy infantry tech" it's much cheaper than a normal tech and quicker to research but only unlocks heavies and commandos, this gives you an opportunity to do an infantry focus but sacrifice your overall tech progress for an early rush/advantage. Or maybe you're just doing to counter the dreaded double scorpion opener.
I think this could add more depth to the game and allow for conventual or unconventional openers and strats.