Heard of all of the above, played AoE II, Battle Field 1942, and Medal of Honor.
I can't really say which one is best because they're all different.
MoH is the best csingle player 1st person shooter,
Battle field 1942 in the best multiplayer 1st person shooter
AoE II is the one of the coolest strategy games ever, but I think Starcraft rules all.
Gotta love the terran marine unit, it rocks. (Yes suh!)
I have played BF1942 and all the expansions that have came out for it.........fun game but I play Operation flashpoint and enjoy. It is a interesting squad level game and also does not require a high end video card and uber processor.......also when I am wanting to use my mind I play Hearts of Iron.
Vietnam!!! That game owns so much! The Hueys in that game rock! My second choice would have to go to Medal of Honor. It's my favorite WWII FPS. Great multi. BF42 would have to be my third choice because it's getting outdated. If they port BF42 to Vietnam... it would own so much. AoE would be my last choice. It really doesn't relate to the other games on your list. AoE is a great RTS though.
Oh, and if you guys are interested in Medal of Honor, Call of Duty, America's Army, or the Battlfield games... you should check out my clan site... --> www.mcgamers.com