The debate rages on. 

Generally, MALES are apt to be "lovable slobs" and "good ol' boys." They tend to be more forcefully affectionate, 
more "in your face." Males tend to be more reliable in mood, less prone to emotional swings. Though sometimes clumsy 
and silly, and prone to acting like oversized puppies, they mean well and are easy to love. 
(Come to think of it, this is similar to their human counterparts...)

On the negative side, males are more apt to test their owners and engage in dominance struggles, especially during the hormonal adolescent months.

Males have obvious genitals, which can make for embarrassing moments if they decide to lick themselves when Grandma 
is visiting. Some males are enthusiastic humpers who will mount stuffed toys, other dogs, sometimes people's legs.

Most males lift their leg to urinate, a consideration if you have expensive shrubbery or lawn ornaments. Some males are territorial markers.
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Generally, FEMALES are more subtle than males. They're affectionate on their own terms. 
They'll ask for petting, then assert their independence by moving away when they've had enough.

Females are often quicker to learn and not as easily distracted during training sessions. 
They are less likely to engage in open dominance challenges, but they can be clever and manipulative about getting their own way.

Remarkably, female dogs also resemble their human counterparts...they're prone to mood swings and emotional theatrics. They can be sweet one day (or one hour) and grumpy the next. 

They are masters of The Dirty Look and The Sulk.

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In some breeds and lines, certainly in many individuals, these sex-based generalizations may be reversed.