I've always used Gatorskins until recently - always found them pretty good, though I did get a couple of punctures at the end of a long Audax day earlier this year so I thought I'd try something else.
Bought some Bontrager Race Lite Hard Cases. Again, they've been pretty good - no complaints really.
That said, they both still feel pretty dead compared to supple summer tyres. I have my Ultremo R1 pumped up to about 130 - 140psi at the back, and that feels way more comfy than the Hard Cases at 100.