Valmy Prussians just don't exist at 1/72nd scale. In fact, I'm not sure you'd find them at any scale in any medium. They were an odd proto-bicorn called a kasket, basically a narrow-brimmed round hat with the front and rear turned up, presenting a semi-circular silhouette (not to be confused with the false-fronted shako the Austrians called a kasket).
Besides Valmy, the Prussians fought in combined armies with the Austrians but weren't terribly active, withdrawing from the wars until 1806. Personally, my plan is to use HaT 1806 Prussians to stand in for their predecessors. If you MUST have them some trimming of the ESCI Prussians' bicorns would probably give you the best approximation.
The Austrians are far more active in the 1st and 2nd Coaltions. The Italeri set mislabelled 1805 Austrians is actually good for up for 1793 to 1798 when the classical helmet was introduced. I'd build those before I did Valmy Prussians.
The HaT Swedish Infantry provides a lot of great figures for the Flanders Campaign, either as Emigre troops like Beon and Salm or as the Hanoverian Guard Grenadiers who were deployed as skirmishers in the Avant Garde of the Duke of York's Anglo-Allied army.
Most countries will still wearing uniforms that were in vogue during the American Revolution. Thus AWI figures can be used for English, Hanoverian, Hessian, Brunswick and Dutch line troops.