The ideal is a balance of the two, but a swinger would do best to error on the 'left' and a hitter 'right' - at least in terms of subjective 'feels' through the ball.
Most folks should learn a slightly more left sided swing, and move towards a balanced swing as they get the 'firm left side' through impact... easier to 'add' the right side than it is to start with that as the key feel.
Some drills....
Drill left hand only swings until you can hit a 6 iron 100 yards with a slight draw (using both hands and letting go through impact if you don't have the strength to do just left)
Drill the same but right hand only, focusing on right wrist bent back
For me, the key balance is the 'firm left side' and the 'right arm throw', in a good swing, I'll feel both, especially the right arm extention 'through' the shot. Take a look at Byrd's photo on Redgoats site for a great example of right arm extention, and picture Payne Stewart for a great example of left sided swings.