As always there are good and bad music made in every era and it all comes down to personal taste. Personally I find the era of jazz and blues to create generally the best music. The level of quality and skill was amazing (not saying everyone was good but y'know...). Like the radio guy on the jazz channel in GTA IV says "from a time when musicians could actually play their instruments". Now this is far from the truth but I can't help but smile a little bit.
I do like the 90's a lot too. The best rock and alternative bands were definately made in that decade. I am split when it comes to the 00'. I watch with fear as dubstep, techno, hard style and whatnot moves through the mainstream and gathers crowds that are uncomparable. However, the music that I mostly listen to (instrumental rock, math-rock and experimental rock) is having a great time, becoming more popular and AMAZING bands have emerged the last few years.
So it depends, 00's mainstream sucks, but the underground shines with light.
Aren't we hypocrites though? We always used to blame our parents for being conservative and not appreciating the great music being made when we grew up, and now we are watching with despise and stubbornness as a new type of music is becoming hip.
Either way, great music is being made all the time, you just gotta know where to look.