I always choose weapons based on a character's personality or a look I'm going for in the character portrait.
I like bastard swords for humans. Couldn't tell you why, but almost every human I played had a bastard sword.
Falchions are popular among my characters simply because it's easy to make 'em look bad-ass in the character portrait with a 5-and-a-half-foot meat cleaver thrown over their shoulder.
Throwing knives are a staple for any character that doesn't carry a bow (longbow/shortbow/hand x-bow, I don't particularly like lgt/hvy crossbows).
My favorite weapon of all time was "Beater Stick". A 400 lbs. main support beam taken from a barn with axe, pitchfork, shovel, hoe, rake, and posthole digger heads driven through it and one end carved to half its original width to facilitate its being used by our enlarged half-ogre fighter as a vicious club during pivotal fights. It had its own wagon. And a theme song.