Choosing between LDO and buck for a noise-sensitive ADC rail

I'm powering a 24-bit ADC and the team is split: an LDO from a 5 V rail is clean but burns power, while a buck plus LC filter is efficient but risks spurs. The analog folks demand sub-10 µV noise. Has anyone characterized both options on a real board and found the buck clean enough?

Good stuff, bookmarked. Will try this approach in our next build.