You're right about Bonaly's deathdrop deserving a deduction. However, Chen's combination spin was simply a huge mess. Lack of control, bad positions on her back spins, and just not attractive. Even if Bonaly's combo spin was a bit slow, she had nice variety of positions and her back catchfoot spin actually gained some speed. I think you were sort of nitpicky about Bonaly's Salchow because although it wasn't the smoothest landing, it was still clean with some good run-out. If you're going to be that nitpicky then Chen's Lutz should also give you pause since it seemed short although it had a beautiful outside edge and height. Also, her double axel had just as good of a landing as Bonaly's Salchow. Bonaly's double axel was better, IMO. Spirals, both were pretty blah to me. Chen had more personality but she really had some messy positions. Bonaly held her positions better but the edges weren't as good. However, I liked Bonaly's transitions in-between her spirals.
Presentation-wise, I actually thought Bonaly was way more "on" and got the music more than Chen who seemed to be trying hard to sell that routine but it just wasn't convincing.
Slutskaya is an interesting case because technically, she was far superior to Bonaly and Chen, but that double/double combo should be at least a 0.4 off of her base mark (were double combinations an actual deduction or just lowering of the base mark in 1998?). I will say that her double axel really was a thing of beauty. Tano axel with excellent control out of it. Also, that SP was horrific in terms of music and presentation, IMO. Much lower than what Slute was capable of.
I don't really care about whether Bonaly or Chen should have been higher, but I do think Bonaly should have been higher than Slute who on her average days is a better skater than Bonaly on her good days. However, that double/double combination was a major mistake on a required element, and back then, the SPs were brutal on missed elements even when other elements did make up for mistakes (as we've seen top skaters who made mistakes in the SP score higher than clean skats by lower-ranked skaters under 6.0).
I would have scored it this way:
5.4/5.6 - Bonaly
5.3/5.6 - Chen
5.3/5.4 - Slutskaya