I've previously registered my personal vote for a 638. I'd like to add that, for any of these snubbies, the best tool you can get to improve your accuracy is a Crimson Trace laser grip. It effectively adds an adjustable sight to your fixed sight gun. More important, it puts the sight ON the target instead of the gun, meaning you can shoot accurately without having to properly align two close points and a distant point in front of your eye - you can shoot accurately from the hip, if circumstances dictate.
Even more important (I think, based on first hand experience of others I've talked to, but not on personal experience) is the tactical benefit of letting threats know that you are armed with a gun that is easy to aim accurately. Some will say you shouldn't let an opponent know where you are or that you're armed, as that will only give 'em an advantage. But I think MOST threats react to the sign of a red dot headed their way the same way they react to the sound of a round being racked into a pump shotgun - they want to get as far away from you as fast as they can. So it improves the chances of removing a threat without having to fire a shot.
But the MOST important value of a laser grip is the incredible feedback it gives when you dry fire the gun. (You DO plan to dry fire a lot, don't you?) Most people are amazed (and dismayed), the first time they dry fire at a point across the room using a laser sight, to see where their barrel actually points while they're squeezing the trigger. The good thing is that you can see WHAT is wrong to begin with, and how much you are improving as you practice more and more.