There are a few decent choices for the King of Battle. To my liking the ACTA British Artillery crew is the best set made. Believable poses (4) with 16 figures to a box. Where it falls apart is that the guns come 1 to a box- just too expensive. I make do with play-set cannons on what appear to be howitzer caissons. Two guns and 8 crew make a battery. Two minor drawbacks to the set is the gunner with the ammo has a ball rather than a cartridge, and the other is that Brit gunners require lots of "surgery" to represent other nations.
I've seen nice work on the HaT site converting Prussians and Bavarians into gunners. I've been using ACTA Grenadiers for French foot artillery. From a distance the painted gaiters don't look too bad.
I was lucky enough to get a number of Italeri French Artillery kits . They a very well done but have yet to reach the painting table. These guns are crewed by guard horse artillery (a couple of over-dramatic poses) that are beautifully executed. Will post when painted.
Another source is the prolific Armies in Plastic. While I really like their Rogers Rangers/Woodland Indian sets, their Napoleonic poses look a bit wooden. That said, they are in production and reasonably priced.