At the moment for Mountain Bike use I recommend the Ritchey Logic pedal made by Wellgo.
It's available only in the Steel spindle until a new variation is manufactured in April. It is widely believed the new Ritchey pedal will be made at another factory. The Ritchey style pedal has shown up under several brand names in the 1996 year and Ritchey's loss of this exclusivity is viewed as a reason for the change.
Under the Wellgo brand name it is called the 94-B and is also to sold as the Cannondale/Coda and Dean pedals.
It is well constructed and even though inexpensive, it doesn't rely on elastomer bushings like the Onza pedal which was the in-expensive champ until the Ritchey pedal. It uses a coiled steel spring retention system.
For Road Bike riders I still believe the Shimano Ultegra 6500 to be the best all around choice. There are many here who still use Time Ti Mag pedals because of the rotation aspects.
There are a few riders who will still insist the Speedplay to be the better choice. These are users who haven't tried to buy spare parts for them lately. A quick read of the newsgroup servers in Europe and the South Pacific begins to reveal a collapse.