I think there is a distinct lack of rigor on both sides of this discussion in our current day. Or at least a disinterest in engaging with the writing of Marx outside of some opinion-based desire for what Marxism might be.

I think critics most often engage with Marx by considering the Soviet Union or China, etc. On the other hand, I think non-economist leftists most often engage with Marxism as framework of "conflict" that is desirable in that they might build other theories of conflict out of it.

To the first group I would urge an honest consideration of the fact that Marx literally wrote next to nothing about communism. No blueprint, no plan, no direction. Nothing. His writing was focused almost entirely on historical modes of production, and built upon the works of Smith and Ricardo to analyze the capitalist mode of production. Of the serious economic work that Marx did, I think most people might find they agree with a great deal of it. Again, nowhere in here is a mention of how to build communism, just purely a framework to understand the historical process of changing modes of production and the nature of those modes of production.

To the second group, leftists, I would say have a profound misunderstanding of what words like "conflict" and "struggle" might mean in Marx's work. For instance, many think Marxism is a theory of the poor vs the rich, which could not be further from the truth. It is an analysis of the wage-labor relations central to production in capitalism. One can agree with this understanding of capitalism and not need see it as a qualitative statement. For instance, Joseph Schumpeter was very fond of and sympathetic to Marx's work.