Best Decade for each Genre?

Rock: 1980s
Country: 1990s
Pop: 1980s
Rap: 1990s
Jazz: not sure, I guess 80s and 90s

Rock: 70s
Country: ?
Pop: 60s
Rap: 80s
Jazz: 50s

Rap = 1990's ; BY FAR! ; that's not even debatable if you ask me as damn near everything of any real worth is from this decade.

that's not even close as basically all of the stuff i used to listen to as a teenager is pretty much from the 1990's (i was born 1979). occasional slight bits-and-pieces in the early 2000's (but basically after the 1990's rap went downhill) but rap largely peaked for me in 1998 all around with Master P's record company 'No-Limit Records' as a larger portion of everything they released from 1998 and older was quality.

but outside of them to name some of the best rap albums of the 1990's...

Krayzie Bone - Thug Mentality 1999 (1999) (he's easily the best rapper from Bone Thugs-n-Harmony and this is easily his best CD and the only one that really stands out from the rappers solo projects in the group)

Bone Thugs-n-Harmony - The Art of War (1997) (easily the groups best CD overall)

Snoop Dogg - Doggystyle (1993) (the 'What's My Name' song is what got me into this one as i still have a recording from the radio on a cassette tape from Oct 22nd 1993 which i would have been 14 years old then which means i got the actual CD not too long after that. obviously, i don't use that tape but i hang onto it for memory sake)

Dr Dre - The Chronic (1992) (this is the CD that got me into music in the first place as i remember seeing the 'Dre Day' video back around 1992/early 1993)

2-Pac(basically anything from about 1996 and older. he's always going to be one of the most popular rappers on a mainstream level as he's someone who won't be forgotten.)

C-Murder - Life or Death (1998) (if there is one rap album that's my all around favorite from No-Limit Records it's got to be this one. but sadly, even he never recaptured the magic of this album with anything released after this even though just about everything he did in 1998 or older on other rappers albums from No-Limit is quality.)

etc (i could have listed a fair amount more but that's good enough for now)

p.s. i still have a large portion of those CD's i had since the 1990's (of which i converted to fit onto my portable MP3 player(if anyone wants anything PM me and i can hook you up for free)). basically it was not until basically my mid-20's (about 2004-2005) when i started to listen to other music as no other music did anything for me until i was in my mid-20's. now, i don't listen to rap much but when i do it's almost always something from the 1990's as some of that stuff still holds up pretty well as after all of these years passed and i moved on to other music and then revisit the rap i used to listen to you can tell some of it still holds strong while other stuff does not.