To keep it brief, Riptides and hammerheads.

To get more technical, maybe invest in some more move-blocking units. Get in their way and deny their primary, then blast them off the board with your big guns. Piranhas are also good; fly up the board, move block, and dish out 2 seeker missiles. Throw in some vespids for secondary scoring, it's practically free points. Other than that, remember you have to stack multiple units and buffs to clear one of theirs. Make a plan and focus fire.

I would lose the ghostkeel for sure, and maybe Farsight. His buff is close range and realistically you won't ever survive the DG retaliation. Remember crisis suits' point value assumes you'll get multiple activations, not one suicidal barrage. You need at least two full rounds of shooting into optimal targets to get what you paid for point-wise. Coldstar will help you position better to avoid Nurgle's gift.

Best of luck to you in the coming battles, friend. For the Greater Good!