Britney: Britney
Bey: Sasha Fierce and 4
JT: FutureSex and 20/20 Exp
Taylor: Red
Kanye: MBDTF
Lana: Born To Die
But to answer your question about what era I'd like to go back in time and visit, I would say any MJ era from the 80s because I never had a chance to live during his prime
Performance / TV Show appearance at least once a week for MONTHS 5 singles with 5 Music Videos (oh wow how little we all appreciated that and now we're hoping we get a 2nd music video )
WW promo tour for the album release We got so much in 2011
Spirit - Leona's curly hair was so beautiful back then.
The High Road - JoJo was way more sophisticated this era.
Who You Are - It's still Jessie's best album, and it's a really good one.
Loose - though not my favorite album by her, it was so awesome how hard she slayed after Folklore's disastrous performance.
Britney - The singles this era were such flops compared to her previous ones, but there were like 9 (?) music videos and they are really fun to binge watch lol. Britney was branching out to different genres with this album and that was interesting.
5 singles with 5 Music Videos (oh wow how little we all appreciated that and now we're hoping we get a 2nd music video 
)