I am a fan of both and their time at the top was hype. Neither of them are goats of their division but hype wise, their careers were insane. Both have a lot of annoying fans but which period did you prefer more?
Slight edge to Brock cause he got me into MMA and heavyweights are just a bit more exciting to me.
How long did either 'era' last?
From winning to losing the title for Brock it was 2 years and a Mir and Carwin fight. For Conor he went 2-2 over 3 years after beating Aldo.
I don't think there have been Conor or Brock eras but if there have been, the Conor era is longer because he was gone failing at boxing so there were more (non Conor) UFC fights then so it wins.
Brock never had an "era"... he's a shit fighter and his horde of "casuals" are a bane to the sport...