Snakes Vs Rats

The other day I saw a very large black snake slither into the lemongrass plant that I thought the rats were living in. This could mean one of two things. Either there were never any rats and all the movement I’ve seen in the plant has been a snake all along or a snake has discovered the rats and is chowing down on them. If the latter is true the snake has won because I keep seeing it around the yard. I’m not sure which is better, rats or snakes. Why can’t something pleasant live in my yard like bunnies or unicorns?