It has gone in waves imo here’s what I’ve personally noticed.
1997ish-2007 PRIDE Heavyweight and LHW had some of the best athletes in the sport but they were mostly over in Japan.
For the UFC around that time Welterweight was probably their best division with talent like Hughes, GSP, Miletich, Newton, Serra.
Then from around 2008-12 LHW was where it was at with most of the PRIDE roster coming over to fill the LHW division as well as the rising and crowning of Jones the divisional GOAT. Plus you had Hendo, Vitor, Rampage, Shogun, Wand, Machida.
Then imo Bantamweight had a brief spotlight with the rivalry between Cruz and TAM. You got guys with immense talent like Cruz, TJ, Cody, Barao, Faber, Assunção, and so on.
Then with the rise of McGregor Lightweight has taken the spotlight as the all eyes on division because despite Conor starting off in the UFC as a Featherweight his absolute zenith was becoming double champ at Lightweight. And you have guys like Dustin, Khabib, Islam, who are other big standouts in the division but in reality Lightweight was great for a long time before that with Bendo, Gilbert, Pettis, and more being beasts.