I did use infantry as I was forced to because of objectives

I took only graviton cannon centurions (they are broken compared to other infantry, and their troop count is pretty high considering that a squad of them is usually 3 centurions to 10 tactical Marines, so no wonder they perform better, as we can get 10 at the same time, and cyclone missile terminators (same reason, to have a better punch in assault, and because Blood Angels do not have centurion armor).
But as I said, early on, infantry vs tanks is not as bad as late game : Leman Russ have only 5 tanks per unit, while predators have 7 (!), and Space Marines only have 10 troopers per unit. 10 marines or 7 Predators? Hardly a tough choice...
Note that Space Marines, terminators and centurions work more or less as I advised :
Terminators for instance have a higher unit count compared to Marines (a terminator company is 60 terminators, compared to 95 marines for a regular company ). Plus the heavy weapons and hit points work almost as I recommended : you get 1 cyclone launcher per 3 terminators HP, if HP represented 1 guy and not 1/3 guy, that would work: 1/3 guy with a launcher, 2 with Storm bolsters (only one currently), so the only thing missing would be to limit the damage to 1 hit point per shot and voila(artillery and AoE should be allowed to do more), we have an unit that has almost the same firepower, but doesn't die as quickly to anti tank weapons, and whose representation makes more sense(currently, a terminator is more durable than a Leman Russ, and a centurion more than a predator).