******Another update: Another 75% off sale in late August.

Mount&Blade Warband and Napoleonic Wars are the ones to get in my opinion.

All Mount&Blade games/DLC are 75% off on Steam .

Warband: http://store.steampowered.com/app/48700/

Napoleonic Wars (DLC) : http://store.steampowered.com/app/48705/

Mount&Blade collection: http://store.steampowered.com/sub/14259/

Community events in Napoleonic Wars such as linebattle events(http://forums.taleworlds.com/index.php/topic,236316.0.html )are quite a bit of fun I must say.

An example of one of the Napoleonic Wars community events:

As line infanry:

As cavalry( some bad audio in the start of it, sorry):

Steam group for public players to check out any events that allow (non-regimental players) :

http://steamcommunity.com/groups/Pub_Regiment

Another example of some more Warband vanilla-like combat via Rome era mod:

eh, I will wait for a frontpage sale for the Mount&Blade collection. seen a lot of those linebattles for npoleonic wars, seems kindof interesting.

Update: Summer sale

@AllenWalker: Actually, this might be as cheap as it ever gets! I've rarely seen anything go for more than 75% like the M&B games are now.

@EquitasInvictus: I believe that post was a whole month old, albeit it is my fault for not writing something about "UPDATE!" in the post sooner.

Update: Another 75% off sale in late August

I'm always interested when these Mount & Blade sales go up but I have no interest in buying an entire collection of games that I may very well hate, and there's too many products for someone, who doesn't know enough about the franchise, to just pick one. 
 
So chances are I will, as usual, pass.

Get Warband and the Napoleonic Wars, you won't regret it! :)

@ProfessorEss said:

I'm always interested when these Mount & Blade sales go up but I have no interest in buying an entire collection of games that I may very well hate, and there's too many products for someone, who doesn't know enough about the franchise, to just pick one. So chances are I will, as usual, pass.

Warband is probably the best one to get I think. Mount&Blade is pretty more outdated in comparison to Warband,Fire&Sword is pretty meh (The Deluge multiplayer mod does it better) and Napoloenic Wars.... check the vids I embed, if you don't like what you see then that's that.

@ProfessorEss said:

I'm always interested when these Mount & Blade sales go up but I have no interest in buying an entire collection of games that I may very well hate, and there's too many products for someone, who doesn't know enough about the franchise, to just pick one. So chances are I will, as usual, pass.

Just get warband. They're all the same game, but Warband still has multiplayer but not the infuriating one-hit-kill aspects of muskets. I made the mistake of getting the collection and really, it's redundant.