What optional rules are popular? Are any considered pretty much essential? FoW seems that way to me.
I've tried only a subset of the optional rules. I like FoW, Mire, and Overrun. I *really* like Efficient Move & Fire. I can do without Excess Initiative.
Fog of War
Limited Intelligence for face-to-face play.
Hidden Units when the scenario calls for it.
I've experimented with Extended Assault and Overrun in solo plays and I have a mixed opinion. I need to figure out the type of scenarios for which they will add to my enjoyment.
I will experiment with Ruins and Pre-Plotted Artillery at some point.