HR zones I like but sometimes external factors can impact quite a lot, ( sleep, hydration, caffeine even time of day. ) Power is far more of a superior metric as it’s instant and external factors are taken out, but apart from cycling with power meters it’s pretty hard. I haven’t done much with map personally so I can’t comment. I guess for me I like a mix of HR zones and RPE. If you can dial in RPE I personally think that is all you need. RPE is so over looked because it can’t be worn on a wrist or chest strap. One of the best at it is a British runner called Emile Cairess, he runs with just a Casio watch and everything is based of RPE. I think he came 4th in the London marathon this way. My 2 cents is HR + RPE = top tier for all forms of CrossFit, conditioning and everything in between