American Independence is very timely with the 250th anniversaries pending so I'd suggest starting there - and moving as fast as possible.
Alas, I think I have what I need - literally over 200 foot units, 20 cavalry units (mostly from Freikorps SYW and AWI figures) and a generous supply of artillery, generals, and civilians for AWI. But I still think it is the best to be 'first'. ECW also is perennially popular, at least in England. The other three are all more specialized in interest so I'd push those to the back of the line.
Now, if you happen to be able to lay your hands on the Thompson's gazelle mold that was made - I got a sample of them so I know it existed in some way at some point, adult male and female, young - I'd be SUPER interested and order several score (literally, probably at least 72 and a bit more to convert to dead animals - and more if it would help get them into production. Quite serious.)