Azores or Iceland? Which would be better to visit in early September? (Crowds, cost, weather, etc.)

Hi! I am comparing the Azores (São Miguel) and Iceland for September 4 to September 13.

I have heard that spring or fall are good for either but my head is spinning trying to pick one place. I know weather can vary a bit in one day in each location but I guess just generally speaking for that time of year.

I know Iceland has been really crowded but I wasn’t sure if September was better than, say, March or April.

Thank you for any help you can provide!