Nothing. I had my kids fairly young so I didn't yet have a lot of the things mentioned here (career, extensive travel, designer clothes.) You can't give up what you never had in the first place.

Sleep and time to myself. We have made travel a priority, bought a house before kids, etc so everything else has stayed the same.

Nothing tangible. I waited until I could afford them.

Intangible - sleep, alone time, personal friendships