Well, it all comes down to what type of RP you want. if you want an Action, battle driven RP we go for the second world War. if you want a quieter with less action RP you pick world war one. Personally its easier to choose the Second World War as its the one that Everyone seems to find easier as the weapons are the most commonly known because they are shown so much in Video Games and movies. where as world war one, not many people could tell you what happened at the battle of Verdun. Not many people could tell you where verdun is. so id say stick with the classic easier option