I'm still working on that
But you assume that I'm trying to build a fleet to counter a ship. Not so much...
Okay, so once again.. The Sova is powerful because:
1. it produces SC for no AM cost
2. it can steal an entire homeworld's worth of income
3. it has a lot of health
4. it can kite while still being all of the above
5. it can create a small static fleet
So.. That means we need something powerful and fast to out-run and out-gun it. Other capitals have lots of power, but not the SC unless they too are carriers, at which point the Sova will still win due to a war of attrition. LRF have a lot of power, but don't do so well with chasing. LF are fast and decently powerful, but get torn apart by LRF (which everyone and their brother will be building masses of anyways). Flak don't fit the bill at all.
I suppose there are two way here:
1. give the other races something long range that can stop the Sova in it's tracks/stop embargo
2. buff LF from 50% damage against capitals to 100% or something. This could throw balance out the window in other regards, but it honestly might not since LF still get shredded by LRF. (That, and I've always wondered how the thing that is made to take down heavy armor is less effective against heavier armor than something made for medium armor).
Since I think we want to stay away from 2 because of the can of worms it opens up, let's investigate 1. What abilities could potentially put a stop to this? I can already think of two that could possibly do so in one form or another: Gravity Bomb and Detonate Antimatter.
In both cases, you have to get in range, but once you do, I think it should be significantly easier for you to take down the Sova. GB halts it's movements and DAM halts embargo and those pesky missile platforms. In both cases, it comes down to acquiring a target in range. This could be done by increasing their range. I'm not going to say that this is a perfect solution and could have ramifications elsewhere, but I think it's something we should at least consider, if only to disregard later.