I like playing with 2 Support Choices. It gives a fuller game, and you can play "doubles" with two players on a side.
Personally, I tend to favor the "horsey" armies.
In the "quality over quantity" category, the most impressive attacking list I've seen thus far - if we're doing 2 Support Choices - has been the Russian Guards with Guard Cavalry and Cuirassiers.
On the defense, I think I'd want Empire-era Russian infantry, with Reserve Artillery and Light Cavalry as a reinforcement that will almost surely arrive before the enemy gets to my side of the board, using the "Home Field Advantage."
French Young Guards with Polish and Westphalian cavalry in support would also be a formidable force: elite infantry core with more elite cavalry.
I was thinking about painting some more Hungarian grenadiers so I can do an Austrian "Reserve" list with lots of cavalry in support. (If you're going to be out-skirmished anyway, then you might as well at least have elites who like to use the bayonet.) But my regular Austrians have always held their own pretty well. The artillery is weak, but those big infantry units can take a lot of punishment.
John Holly's Brit list is pretty solid: he has the Light or Infantry Div core (depending upon his mood that day), plus the Brunswicker allied contingent, plus Light Cav in Reserve. In the last game against Barry Katz's Peninsular French, plus Dragoons, John stopped the frogs in their tracks.
On my painting table right now, though, are some Plain-Jane "Liberation" Prussians.