Parents of 4 kids- advice needed

How was the transition going from 3 to 4. Currently have 3 kids and it’s been consuming me on whether we should have another. I have 2 girls and 1 boy. 6,5,4. This would be our biggest age gap.

Did you notice anything with 3 that’s better than 4 or visa versa. Any advice will help. My clock is ticking and I need to make up my mind.