I seem to be in the minority when it comes to Death from the Skies, in that I'm looking forward to my first game with the new rules, but anyway...
I've been a big fan of the Razorwing since it was released. I have two and I usually run both. Arriving from reserve and dropping four large blasts per plane always does damage and tends to get my opponents' attention. This is good because while they're dedicating lots of firepower to bringing down the Razorwings - which have already done what I wanted them to do - that firepower isn't being directed at my other units.
I also have a Voidraven, which I don't have nearly as much luck with. I somehow seem to always roll max scatter with the void mine and it's easy to miss with the small blast implosion missiles. Plus it's expensive. However, since two are required for a flyer wing and for our formation, I suspect a second will arrive before the end of the week.
What I haven't used are the Craftworld flyers, the Crimson Hunter and the Hemlock. Before I heard of Death from the Skies I'd considered getting hold of a Crimson Hunter or three to handle air superiority duties so that I could use the Razorwings as dedicated strike fighters, but now I'm not so sure.
I'm likely to be going up against Tau and Necrons, mostly, although I may also run into Stormhawks and the occasional Valkyrie.
I'm interested in what other people would be looking to add after the second Voidraven. Any opinions are welcome.