Best HD camcorder for recording sports
Nothing really. All recent camcorders are more than enough for what you want.

Two things to look: 


That shutter speed can change so that you can define how smooth motion you want
That they offer fast zoom/focus capabilities for sports.


Any recent cam-corder from major companies already covers this.

If you want quality sound you should also look for a camcorder that has an external mic jack so that you can connect your own microphone. This raises the budget a lot.

Unless you are a professional I would stay away from using a DSLR for sports filming.

I personally own a panasonic-v250. I also bought it for sports filming.