Right, well in battles i think skirmishers are much better since there are not many rules restricting you, many people have rules for light infantry like max 3 man spacing, you have to stand up etc.
Quality vs. Quantity, the rifleman can fire more well aimed shots while the light infantryman will spew out a couple more less accurate shots.
Bayonet vs. Rifle butt or sword bayonet ; You should not need to have a bayonet, if you are operating out of distance from any other component of your team you are doing it wrong as a commander. Also, you can block perfectly fine with a rifle as with a musket. Remember that riflemen and lights support the line infantry, not the other way around.
There are tons of incompetent commanders who think they are their own army and everything works around them, and stay at the back of the map doing nothing and eventually gets isolated and killed by cavalry, it doesn't matter if you have a bayonet or not, if you don't kill enough of them with bullets you will die. Period.
In the historical aspect, light infantry were easier to train and supply and required less able men. However skirmishers required a certain kind of man that was hard to find in many countries ( The French had good luck with this ).
If you do rifles right, you will do better than someone doing light infantry wrong and vice versa. It's about their use, not their armament, organization etc.
If the light can only bring the same amount of men as the rifles and they go against eachother, considering they are of equal skill, the rifles will win.
But as with most things in life this is very situational.