For my 18 ex raids none of them is gold gym (not sure if they are bronze or silver but for sure not gold!) but i do avoid those ultra popular and crowded ex raid sites
my first ex raid pass, I got it when my gym badge was early silver, my 3rd pass the gym badge was bronze but close to silver..
So, just keep active on those gyms, raid is the fastest way to rank up (1000 pts per raid?) but occupying or fighting gyms oso increase badges points but slower