I want to give a different perspective.
Do what is common practise in your institution/region (i. e. what your collegues or other comparable people do).
Here in Austria, it seems to be common practise to list all your titles (maybe except for BSc/BA if you have a MSc/MA because people are not so used to these two titles). I often see multiple doctor titles and honoris causa titles in signatures.
In my view, many people here see a signature (if there is any) as a place where you state your "official" name - and, at least here, this includes your titles. "Bob" in a signature would certainly be viewed as unprofessional and strange. (But then again, I am not sure if the commenters suggesting writing "Bob" are serious or joking.)
While many people on this site view many titles as "bragging", not including them can certainly interpreted as an insult to the others - like you are saying "you guys including so many titles are pretentious".
So in short, do what your environment does.
However, I have never ever seen someone stating the field they received their titles in. (Although there are titles like "BA (FH)" (FH meanging Fachhochschule, "university of applied sciences"), which appear sometimes. Probably they have to be stated in exact this way.)