All right: barring the fact that I personally wouldn't be all that pleased to see much of any war, barring butthurt whining about asinine stupidity of matching up ridiculous crap, and all that: these are some matchups I could be interested in.
I think it could potentially have been pretty interesting to see the Mongols run up against the longbow-and-defensive heavy infantry armies of Edward I and his successors. Mostly from a tactical point of view. I think it'd be kinda neat. Along similar lines, I'd be interested in seeing how well the Indo-Pahlavan heavy cavalry horse-archers and lancers of Gondophares would have fared against, say, the Satavahanas' mixture of heavy infantry (in both the Greek and Indian guild-warrior variants) and longbowmen. Admittedly these aren't particularly interesting from any point other than a tactical one, but still.
I always was rather impressed by von Metternich's aversion of Italian war in the early 1830s with France, but abstractly a war between Austria on the one hand and France on the other, with a Neapolitan wild card, an unstable Papacy, a (shockingly)
pro-Austrian Piedmont-Sardinia, and excellent scope for expanding a war into the Low Countries and Germany would be interesting. Presents a rather odd operational dilemma for France, their best option is hitting up Naples but after that it's a tossup to see who can hold (or take and hold as the case may be) Lombardy, which would be the key to any war.
Similarly, 1848 presents a few good possibilities. Outside of the lunatic schemes of von Arnim-Suckow, there's always a good chance for Cavaignac to have entered the Italian war, or taken the opportunity to have a jolly revanche against the Germans and the Belgians. It'd have been a proper revolutionary year instead of a lame one.
We were just having fun Dachs, but you took it too far.
Self-fulfilling prophecy.
Who the hell is that women in your avatar Dachs?
Michelle Branch.