>>149409954
Probably my national bias, but I've always thought cross country skiing is the most underrated mix of the two.
Hard to find comprehensive lists, but out of the top 10 VOMax ever recorded, at least 3 are XC skiers, which is huge considering it's a sport done by about 5 million people worldwide while something like running is around 2 billion people. So the endurance requirements are insane.
Simultaneously you need full-body strength with a huge amount of core especially. Pic related is the current best skier in the world and doesn't exactly look like your typical cyclist or runner.