I found this one harder to answer than which Console Gen was best because every decade expanded the gaming landscape into what it is today so it's hard to say which was best - it's simply down to what you value most. In terms of personal enjoyment I'd go with the 90s because that's what I grew up playing and still to this day love to go back to (I also answered 5th gen was my fave in that poll). But here I've voted for the 00s being the best.
In terms of bringing the gaming world to what it is now the most important stuff happened in the 2000s as far as i'm concerned. The 6th Gen was excellent in that it offered 4 strong consoles to kick us off this decade (yeah ok Dreamcast launched in the late 90s but saw most of its life span in the early 00s). This is also where we saw the start of online gaming, with the Dreamcast, that was then taken to the next level with the introduction of Xbox. It also saw consoles being used more as essential home devices rather than gaming platforms thanks to the PS2 also coming as a DVD player. Then the following gen brought us HD gaming and the bizarre yet beloved Nintendo Wii introducing casuals to gaming more than had ever been done before.
Handheld gaming also became more interesting - the 90s was dominated totally by the Game Boy and IMO the weak follow up of the GB Color with very little in the way of competition. The 2000s started with Nintendo offering a true successor with the awesome GBA (and even more awesome SP which brought backlight and a re-chargeable battery to gaming for the first time) . Then we finally saw Sony enter the fray with the most powerful handheld yet and Nintendo responded with some clever innovation of theirs with the DS. I just felt this made everything better as far as choice was concerned. For me the Game Boy was the console for when you were travelling but now we had handheld consoles i'd sometimes pick over the more powerful home counterparts due to the different experiences on offer. This is ultimately what tipped me in favour of voting for 00s over the more exciting yet more flawed 90s.
If i was to rank it i'd go 00s > 90s > 80s > 10s.
The 80s really set up gaming more than any other decade so you could argue it was the best but for me the developers were still figuring out what to do and could only work with limited hardware. In its favour this was easily the best decade as far as arcade gaming is concerned so it wins on that one. Then the 2010s for me has done the least in terms of bringing gaming forward and adding innovation (maybe this is simply because there are no more proper graphical jumps anymore and we've seen most of what the industry can offer - I hope i'm wrong though!) o this is why i've ranked it last. Still had many great games and consoles though - I absolutely love the Switch!