There are a lot of variables including time frame.
I'll try and break it down as fairly but simply as I can
1.Bigger (attendance/resources)
Historically bigger: Notts
Currently bigger: Notts
On course to be bigger: Still Notts but Stags closing the gap
2.Better (players/results/league position)
Historically better: Notts
Currently better: Stags
On course to be better: Stags but can change week to week with results
3.Significant (media and neutral fan perception)
Historically significant: Notts
Currently significant: Stags *Clough effect
On course to be significant: Stags *as above but could change with results
So based on the above on Sunday 15th November 2020, who is Nottinghamshire's no.2 club?
Maybe everyone could agree to say that it's no longer as obvious as it once was.