In order of preference:
#1. France, best leader, best cavalry (cuirassiers) and best foot guards.
#2. Austria, cuirassiers look almost as cool as French ones, and what's not to love about their Hungarian Grenadiers?
#3. Prussia, best hussars and very interesting foot guard units. Awesome hats.
#4. Russia, partisans, but that's it.
And lucky last...
#5 United Kingdom, black and grey and more black and grey. From the line infantry, to the foot guards and to the cavalry. Boring. As cool as bagpipes and Scotsmen are, the United Kingdom are still my least preferred.