When I was little I didn't have to worry about a getting a defensive head or an offensive one, but it seems now that there are huge advantages to playing with position specific heads and shafts. Defensive heads are made of a stronger plastic that allows them to be more stiff and durable. This allows for the head to take a beating without it breaking. Defensive heads are also wider so they can scoop up ground balls easier and so it is easier to catch with a long pole. The top 5 D heads are as follows...
1- STX Hammer 500: This is the upgrade from the most popular D head, the Hammer. This new head uses some newer technology like C-Channel and a new scoop design allowing for quicker ground balls and reduced stress on the sidewalls.
2- Maverik Tank: This is Maverik's only defense specific head and it was done very well. This head is extremely strong and strings up a nice pocket. The tank has a flatter scoop shape allowing for easy ground balls.
3- Brine Triumph X: Brine took the strongest shape, the triangle, and put them all over this head. This head without a doubt is one of the firmest on the market. There are plenty of sidewall holes accompanied with a nice face shape to string up a nice gem of a pocket.
4- Warrior Regulator X: Although this head is not position specific, it can work really well for an advanced and more offensive oriented defenseman. The more pointed scoop will make ground balls more difficult, but the aggressive face shape and strong plastic makes up for that.
5- Nike Alpha U: This head doesnt get a whole lot of love because it isnt the prettiest but it does perform pretty well. There is a thick piece of plastic right on the side of the head that makes it look weird in my opinion, but for what it was designed for, it does the job pretty well.