The Sonicare toothbrush is probably the most awsome one I have ever used.  It is convenient, always charged, ready to use.  Just screw on your personal toothbrush.  It has a timer that pulses every 30 seconds or so and shuts off at two minutes.  If you use it properly, your teeth always have the feeling that you have just come from a cleaning at the dentist.  I find it also a great way to massage the gums and keep the circulation good there.  Far above and beyond the hand powered toothbrush.  If you are looking for the best, this is it.