Here are some thoughts:
Person Note, Research Note, Marriage (ie Relationship) Note and Fact Note can be included in a Register Report (and most kinds of reports where they can be added - like custom reports, etc.) You can choose individual notes not to print if the global print is turned on, by selecting the "private" option (the padlock icon.)
Fact Notes do NOT sync to ancestry (nor upload with the old upload process).
Source Notes or Source Citation Notes never appear anywhere in any report. As the years go by, you may be inclined to forget about them because they are "hidden" from view. (I usually add source detail transcriptions (ie census) to either the fact note or to a Note Pad file that I attach to a fact as a Media item.
Sometimes I will do a bit of both. For example, I may transcribe a biography (or copy / paste if in text format) in a Fact Note of the person being sketched in a Custom Fact called Bio-Sketch. I may then attach a PDF of that bio/obituary or a copy the transcription into a Notepad file and attach one of these as a media item to an obituary citation that is copied and paste-linked to all the other people mentioned in the bio or obituary.
I almost always make research notes "private". It is for speculation, emails with folks, copies of stuff that "might be him or her", etc.
Before FTM had fact notes, I kept virtually all of my notes in the Person Notes. When FTM came out with fact notes, I thought it was a good idea to keep large volumes of stuff catalogued. However, sometimes I miss my old notes style of having all notes in one place.