I think you are underrating Harper as a difference maker. While he is a career 900 OPS, the last 4 years average over 950. That is pretty good. And is it fair to compare career numbers for a Bobby Bonilla who made his debut at age 23 versus the growing pains of a kid who made his debut at 19? And when you talk about "vibes" I think you are talking more about personal dislike for a player or his style than whether he would be a good player. And Bonilla was pretty good through his age 34 season. It was not his fault he signed a really long contract and his WAR stats are colored a little bit by his willingness to play a position like 3B for the good of the team (like Harper is playing CF now for the good of the team).
Harper's defense has slipped a bit in the past year but it is hard to tell if that is permanent and he is athletic enough that he should be fine in a corner for the next 5-7 years. And all the criticisms about his being "inconsistent" may be almost completely colored by BABIP. Last 4 years of OPS and BABIP:
2015 - 1109 OPS/369 BABIP
2016 - 814 OPS/264 BABIP
2017 - 1008 OPS/356 BABIP
2018 - 895 OPS/272 BABIP
First half this year 833/226 - second half 1129/453
I also worry much less about guys like Santana and Bour. You fit these role players around your stars. If we sign Harper I would be fine trading Santana and eating some money. Frankly Santana may just be a bad decision on the club's part as he had decreasing power last year too. Bour should be non-tendered anyway if we still have Santana.
This club needs a big bat in the middle. I would prefer Machado because he is more important defensively. But I am not going to say No to Harper if he is a realistic option. Harper is good enough that we rearrange the other pieces on the roster to accommodate him. We did that for Santana last year and Cabrera midseason this year. They'd do it for Harper too.