Jakob is about to turn 20, he will be 13 months younger than McLaughlin. Both very promising young talents who are already world class. Who will hang the spikes with a better career? You can define better career however you'd like, but just back it up with good points. I'd say more medals, faster historical context, etc all should factor in. As it stands now, I take Sydney, as she already is a bit ahead of Jakob with global senior medals. Jakob is also a year younger, as I've mentioned, so it's worth noting that.
Jakob:
3:28, 4:50, 13:02
5 European Championships, counting Juniors
Silver and Bronze at world juniors
5-time Euro XC champion
A 4th(1500) and a 5th(5000) at the world championships
Has more medals, because he runs two events with regularity.
Sydney:
52.23h, 50.07
Gold at World Youth Championships
4x400 Gold in World Championships
Silver in the 400h in the World Championships, behind the fastest runner of all time.
American Junior Record holder in 400h
Fun facts: Both have great track family backgrounds. The Ingebrigtsens are pretty well-known here, but Sydney's brother was also a silver medalist at the world junior championships, and her father competed at the Olympic trials.