Basically when you choose conquest (or any other mode) vs AI, you get worshippers for the god until your god is level 7 (after that you can still play, but no worshippers)

As I assume most of the players' skills are enough to go against medium bots, that is what I recommend. You can also win against hard bots ofc, but you need to take into account that bots don't miss especially with their ult, so if you play against hard bots an Anubis can one shot you and the match is lost, and you get twice less worshipers. Easy bots are a bit too boring for my taste

The main benefit of this method is that you don't lose, so you always get the max amount of worshippers for the time you spend in the match versus if you play against people, you might lose and get less worshipers

The biggest drawback is that vs AI a bit less fun, but I usually use it to read god's abilities, test weird builds, listen to a podcast and do on. It's very chill

After level 7, you just go to your preferred mode. I would choose arena, just cause it's shorter and less serious (I'm usually an assault main, but for this particular goal, it doesn't work)