Which flash is best for d5000?

I'd to buy the flash for my nikon d5000 but i'm not sure the best fore

Without a budget, the SB 900. Has a sync jack, longest zoom head of any Nikon flash, compatable with the CLS system (although you might might an SU800 with the D5000), swivel and tilt plus the most power of any flash for the Nikon.

The sb-900 is the top of the line Nikon Flash. That being said it would cost you almost as much as you spent on your camera. The sb-600 is not as powerful but still is compatible with the CLS system. Your other option would be to find a used sb-800 online. The most important thing that will make a flash more useful to you is the ability to move it off your camera and trigger it remotely.