Do I use a plural or singular verb in this sentence? Is one more accurate than the other?
I think it should be plural-agreeing “have” (unlike others who have commented so far). Does the subject of the verb refer to more than one thing? If so, the plural-agreeing form should be used.
Then we need to decide whether “our work and others’ work” is just one thing or two things. If our work and other’s work referred to just one thing, as for example in some collaborative effort, it is that single work that would be referred to. I don’t think that is a possible interpretation, here. Maybe it would be if if the reference was to “our and others’ work” (as compared with “our and others’ works”).
I don’t see the relevance of “work” being a mass noun. I say my work and your work “are the same”, not “is the same” (though it’s true I could say “our work is the same”). But what does that have to do with whether “work” is a mass noun? I could say to my wife that my son and her son is late, yet again, though “son” is not a mass noun.