Well I was in a game yesterday where the guy had an army of about 50 illums and 3 cap ships on a heavily defended planet with reapair stations and gun turrets, me and my ally had him cornered and we had captured the majority of the planets and destoyed his other ally. Because I had so many resources I though i'd try a few tactics against him and I was quite suprised as to how good illums are against stuff which is meant to counter them.
First I though I'd just build a fleet of carriers with fighters to take out all his illums and then finish off the cap ships later, I had about 35 carriers full of fighters with fully aupgraded autocannons and a lvl 6 sova capital ship. I sent them to the edge of his gravity well so I couldnt be targeted by his gun turrets and unleashed the fighters, to my dismay the fighters would rather go after his structures and stuff they where not suited to than go after his illums, also they would spend ages flying to the other end of the gravity well to chase down a single bomber that had just been replenished on about 25% health whilst his army of illums started closing in on my carriers. I phased to another planet before they got near to me and tried again this time targeting the illums manually. Even when attacking the illum a target they are meant to excel against they seemed to take ages to make a dent, I followed one illum that they where attacking and it took about 30 seconds for them to take it down. In the end I just left my carriers on the planet attacking, they where guarded by about 15 or 20 of my own javelis also and the sova and a dunov but the capital ships where quickly dispatched along with the carriers and I had hardly dented his army at all.
After that set back I though id try again with somthing slightly differnt, I still bought about 20 carriers and another sova and dunov but this time I built about 120 acova scout frigates as they have 200% damage against illums which means that 3 scouts would do 24 dps with fully upgraded lasers. I phased over to his planet again and left my carriers on the edge whilst my scouts attacked him, by now he had about 60 illums and still had his 3 capital ships, the scouts destroyed a fair few but the problem was they died so quickly they didnt have much of a chance. I quickly phased back and by now I had produced about 80 new scouts at my own planets. He followed me so I sent my army over to my 3 repair bays and gun emplacements to defend. He had also built his own army of about 40 scouts which along with the illums quickly wiped out my 80 scouts and then my two capital ships and carriers.
In the end he just gave up as he knew he wasnt going to win, but the fact that I built all the correct stuff that is meant to be good against illums and none of them worked made me think that maybe the game is broken?