Things to consider:
Depends on the bike, Where and How you ride, (understand the type riding you will mostly be doing). Radial or Bias ply? Loaded- w/Passenger- w/Passenger & luggage- or Solo
There are several brands out there offering different handing and wear characteristics. If you are an agressive rider, and want handling on twisty roads, choose a tire like the Avon Venom, or Metzler 880. Metzler's are a harder compound and seem to last a little longer than the Avons, but don't seem to corner quite as nice in my opinion. The Avon rears tend to run a little warmer than the Metzlers too. Both are good tires in wet or dry conditions.
If you are a highway rider & tour mainly- loaded- I think the oem Dunlops work fine- (D402's HD tires are the OEM tire) they work very well, a rear will last 8-10k miles, they are smooth on the highway, and channel water well.
If you ride fully loaded most of the time- make sure you choose a tire with the proper load rating-
here are some links you might look to for more info on tires:
http://www.soundrider.com/archive/tips/tire_sense.htmhttp://ezinearticles.com/?Motorcycle-Tire-Basics&id=530176http://www.motorcycle.com/buyers-guide/buyers-guide-to-motorcycle-tires-33369.htmlgood luck