Sorry, I don't think Harper is close to those other three going forward, but if you want to count on him repeating his amazing season from four years ago which he has yet to come close to since then, more power to you. Those other three are great every year, but more importantly, if they're not crushing offensively, they're still providing a ton of value in the field. Harper is doing the opposite. Machado you can mark down a bit for his sometimes dirty play, but to me he is still clearly a more valuable asset (on the field) than Harper.
Also as an aside (I just learned this in the last few months), the current sabermetric conventional wisdom on Coors Field is that the COL hitters are unfairly impacted by pitches moving so differently against them in home and road games, to the point where guys like Arenado and LeMahieu are actually underrated in reality by people just looking at their splits (again, I did this myself until pretty recently). Someone linked a whole string of these articles on Twitter earlier today, which I don't see again right now, but Chris Iannetta's history is worth looking at since he was on COL, then three other teams, then back to COL last year.
"For example, over the past 10 seasons, the Rockies scored 4,596 runs at home, unsurprisingly the most in baseball. But over the same period on the road, they scored 3,089 runs, the fewest in baseball, 151 runs behind 29th-place Houston. In order for both of those things to be true, either Coors Field would have to elevate baseball's worst offense to play like its best, or a middle-of-the-pack team would have had to receive positive effects at home
and negative effects on the road -- which seems far more realistic. You can call that "the Coors Field effect.""
https://www.mlb.com/news/dj-lemahieu-leaves-coors-field-for-the-bronx/c-302622392