M590 CQB, or M590 Military both are my favorites for their low spread. Any one of the spas-12 family is second because they have a lower spread than the other two. In my eyes the double barreled and Rwhatever are the worst because their spread is horribly large. Yet if you can't aim I hear the R one is nice, because it spreads like MAD! Doesn't kill, but it hits.
The more shot I can put in them without being in their face the better, so I pick the M590 series.