This is a very broad question and is more a matter of
opinion
However, Marxism takes a very extreme view of society,
essentially blaming the bourgeois (capitalists) for societys
problems, they believe that they control society through ideology
and other means.
On the other side of the spectrum, Functionalists paint a rather
perfect picture of society, that is runs smoothly.
In my opinion, i think that Marxism is more realistic, but i
would not agree with al of their views