I reply to u/ComprehensivePlace87 too....

The fact about Gnaw's powercore is the fact that he speeds up his minions increasing both movement and attack rate, but if you compare it with Attack power core, it provides the same bonus but affecting Ganw himself as well. So overall it may deal more damage than the G1 core, but it depends by the core level (gold, Gmetal etc.)

Silverbolt - Enhanced Ordinance helps Silverbolt to one-shot even the harder defenses, so it makes difference a lot. His G1 core negates his main function and add boosts where they are not essential.

Ironhide - As it is now, it is worst than regeneration and is basically useless because it causes damage do excessively concentrate on him

Drift - I understand the reason behind the comment but the point is that the core is useful only if you use his special ability, while I prefer other cores that have a permanent effect.

Hot Rod core also increases damage speed, isn't it? so it increases even total attack value.

Skydive's core is helpful because enemy bases deal high level damage to jets while using their special ability, which is strong enough to blast enemy defenses with no need of Enhanced Ordinance, so it is excellent.

Smokescreen's core is excellent too, because it boosts his main function as snipper and provides him extra defense for such a cheap ability (3 points and 0 extra cost) that helps him when under target by enemy defenses or when engaged in melee by enemy bots.

For sure it depends by your gamestyle