I voted "other" because the groups I play in use different methods.
In the d20 Wheel of Time campaign, fights are these days run on a mapgrid with miniatures - the DM having recently decided it was necessary. Prior to that, and in other games I've played with my university friends, we've used pencil sketches to establish the battlefield, and just moved Xs or initials of characters or players around by erasing and rewriting them.
Hong's game tends to use grids and little cardboard figures.
When I run, I intend to use a battlemat and either eraseable markers or some kind of miniatures - for a while in a Planescape game the DM used a grid stuck to a corkboard and coloured pins, and while I wouldn't use that method I might consider counters rather than either metal or plastic miniatures (since most of the people I play with can't or won't paint, and no-one's interested in collectible pre-painted plastic).