1990's, by far.

It was classic after classic on pretty much every system that mattered. Though if 10 years outside strict decades are allowed I'd say 1994-2003 were the Golden Years. Want to include 1993 but then it would be 11 years... Whatever I'm including 1993.

By the way it's kind of funny you seemingly couldn't come up with anything to describe the 2010s in the poll!

That's way too optimistic for HL3.

Nineties

UC4 spoilers removed - VXIII

Definitely 2000s.
Most and best things happened there.

Late 90's. Early 2000's on the PC, when developers were mixing genre's and taking risks. *sigh* The golden years... You just don't get games like Sacrifice or Dungeon Keeper anymore.

You cannot take risks anymore, since costs are so high, just look at some games like Tomb Raider and Bioshock Infinite to notice that costs skyrocketed. 

Thank you so much.

2000-2010

DS Era had a lot of great games

With Tomb Raider you have a point to a degree, although that's Square Enix and we all know the sheer lengths they go to with their needless extravagence.  Bioshock Infinite however is purely a tale of horrible, horrible mismanagement.  It cost a lot but not because it should have. 

Really the problem today is that most of these companies break EVERY rule when it comes to managing a creative venture.  They are factories manufacturing mass inefficiency.  But not all.  Nintendo gets a lot of bang for buck from all their projects.  Even Xenoblade Chronicles X is made by a team and on a budget that is admitted by Takahashi himself to be relatively small for the industry.  Bethesda Softworks manages their business quite well.  CD Projekt Red too.  Sony's studios tend to have a good handle on their costs as well.  What I'm saying is, the cost to develope has gone up but a lot of it is on the management, not the tech.  Shoot, the tech out there is actually making development *easier* in many ways.