WYR travel the world and have one child, or give your child a sibling and do less?

Hubby and I have a 4 year old, we take several trips a year, we’re planning her first international trip for the beginning of next year. For the longest time we have been saying we want 2-3 kids, and eventually not travel as much since more kids means more $ and time, etc. I’m now toying with the idea of keeping our 4 year old an only child and be able to travel and do more things with her. But I can’t decide which is better in the long run - giving her trips & more as an only child, or giving her a sibling and doing less travel and activities?