I'd go SYW / Austrian War of Succession (which are pretty much inter-changeable uniform wise).
I came the other way - SYW to Napoleonics and I'm very happy having both - they are very different tactically if you ignore the a-historical possibility of column of attack and square (which certain gamers employ 'because they could' rather than playing 'what they did'); don't make it make it a Napoleonic game in different uniforms. Historically, it's linear, linear, linear and it plays wonderfully (and differently from Napoleonics) as such.
The mix of infantry / cavalry is also much more balanced than Napoleonics - if you like painting cavalry (as I do) you'll love it. Talking of painting, the uniforms are less complex than Napoleonics with fewer belts, especially if you choose your figures carefully (having piled their packs, etc.). Even so, they really do look good. I went Austrian/ Prussian / Russian.
I have a number of periods now and it's still my favourite because it plays so well. No squares, no skirmish companies - just long lines of units in line. It's so simple the rules actually work most of the time. I can't recommend it enough - though I do try.
Finally, just as a BTW. You also have the option to do this as a 'imagi-Nation' period and make up two (or more) sides to your own tastes. As I get older this becomes more and more appealing but, too late for me. I'm going to do Far East dark ages for this - kinda, Back of Beyond meets the Water Margin.