How to implement contradictory comments/suggestions from collaborators? Every paper that I have worked on originated from the following timeline: a small team works on data and obtains results; one member is designated first author (always the one who did the biggest chunk of work); first author elaborates a draft version of the paper (may request other members to write one or more sections) and sends it to the rest of the team; all the other members send comments/suggestions; first author implements comments/suggestions and sends a new version; iteration of the process until everyone is happy with the paper.  

Background: My field is Astrophysics. Even though the methodology behind writing papers varies from field to field, this question should be useful and easily applied across multiple fields. The viability of this methodology should not be the focus of this question.

I am currently writing a paper as the first author for the first time. Whenever I get comments/suggestions I always try to implement them and if I get more than one suggestion for the same thing, I try to find a mid term that allows me to accommodate every contribution. However, sometimes this is just not possible. As an example, I recently got contradictory comments regarding one paragraph in the introduction: one of the collaborators said "Delete it, we don't need this", the other said "add X, Y and Z". I cannot possibly implement both, as it is not possible to both delete a paragraph and add more information to it.

So, I can summarize my concerns in the following questions:


What factors should I take into account when prioritizing a comment/suggestion (e.g. personal preference as the first author, expertise or reputation of the collaborators who made the comments, ...)
How to professionally address comments/suggestions that were not implemented/had to be ignored? Will it offend a collaborator if I don't use one of his contributions? Should I contact that person stating that I did not implemented comment A because B?
Does the answer to this question change in case of trivial (such as rephrasing and paper structure) vs non-trivial (such as results or other relevant scientific contributions) comments/suggestions?


(I find this question to be significantly different from this one as I am looking for insight regarding collaborators that are contributing to your work and that you intend to collaborate again in the future. The mentioned questions are about (anonymous) peer-reviewers who are not working with you and are trying to make your work publishable.)
I handle conflicting suggestions as follows: Consider all suggestions for this point, work out a suggestion based on the other suggestions and send an email to all collaborators and write something like "In this respect I got conflicting suggestions namely... I would suggest to proceed as follows... because... ". 

It would be best to collect all the points of conflict in one message. 

You may reduce the number of conflicts a bit by adding another step to your workflow: Before starting to write the paper have a session/discussion about the structure of the paper, its focus and the notation. This costs some time and be difficult, but can considerably reduce the number of conflicts. Especially you may point out that some issue has been already discussed in this session. 

Oh, and by the way: I would not suggest to encourage all coauthors to cc their comments to the whole group of authors and have the discussion like that. Then the thread may loose focus pretty fast and things may get messy.