Three, old GW gaming mats. They've seen a lot of wargaming action over the years.
The following will be my opinion – so probably not worth much.
The Horse & musket era suits wargaming more than any other period. It has a 'paper, scissors, rock' aspect that translates nicely to the artificiality of table top gaming.
I think this is even more true of the SYW.
I also game Napoleonics so I'm quite aware of the differences. There's a sort of stately elegance to Age of Reason games. No nasty attack columns, just lines of well disciplined infantry who tend to do what you want them to…until they don't. No swarms of skirmishers – the Prussians in this game had none even if those Croatians caused us some issues. Artillery is a step down from the killer it would be later. The better drilled troops of the era allow you to concentrate a bit more on "proper formation". Cavalry regiments in squadron lines, the passage of lines with your infantry, marching onto a battlefield & deploying from column to line etc.
And the uniforms. Of course, Napoleonics can be vulgarly showy, but the simpler styles of this era just look good.
And finally, it's always about the history. It's fascinating. I think we game more actual battles for this period than imagined scenarios. There's so many great encounters to explore.
But, as always, to each his own.