What is the best DLC to get first?

Hello organ harvesters, I recently started playing Rimworld the other day and it has been all I have thought about since, every waking hour of my being wants to be playing or thinking about the game and the organs that could be getting harvested and sold.

I’m on a very tight budget so I can only afford one DLC for a few months so I’m looking for which one adds the most fun to the game and any bonus tips and tricks are more than welcome