I listen to a gaming podcast called Talkradar, and one of their questions of the week to listeners seemed more apt for the GOG crowd than their crowd.
So, What now defunct publisher/developer do you miss most?
I'm gonna have to go with Oddworld Inhabitants.

It's a tie for me between Black Isle and Origin... RIP.

Bullfrog Productions. I'd love to see more sequels to games like Populous, Dungeon Keeper and Syndicate.

Gametek. Their game show video games were unparalleled, even as I went back to one earlier this week.
BJ

Black Isle, Bullfrug, Adeline, Westwood, Troika and many others.... =(

All of them. The more the merrier.

All of the above, but I really do miss 3DO, I know some of their game were godawful. But I always wanted a squeal to Battle Tanx: Global Assault. :(

Valve ;_;

XD Lol. It's ok, just hope that Steam doesn't get ANYmore screwed up than it is. Lol.

Troika/Black Isle (They were practically the same dev company), by far. There's a few others out there that were decent, but none I miss so much as Troika.
Origin was good. "We CreateD worlds"
(Bold works, but Italic doesn't?)

Yup, Bullfrog. And LucasArts, way back before the "great stupidity" kicked in.

All the above, and the classic Sierra Online, headed by Ken and Roberta Williams. If only Activision could wake up to the awesomeness they are sitting on, and give those classic a fair treatment...
I would say LucasArts too, but they seem to be coming back to the right track. With a vengeance!

So many mentioned Troika which I shamefully forgot about it. They made my favorite game Vampire: The Masquerade- Bloodlines

Another for Bullfrog. Probably 'Ocean' though they (more or less) now exist under a different name and staff.

EA. The real EA who were daring, innovative and imaginative and not this soap opera style actor replacement where he's 20cm shorter and has a completely different voice
Ahh Ocean, the mainstay of the cheap & slightly disappointing game crammed into a box you could use to house a small family but only contained a single disc and a leaflet on which way up to insert it in the drive...