In a street engine what is more important in the cam being used? Would you want more duration or more lift and why? I think a longer duration would be more reliable because it would put less strain on the valve train components. Anyone have advise?

 

I don't think you can just pick one over the other - as your missing a variable.

the 3 factors would be lift, duration and head flow.

High lift would be useless on heads that don't flow well at higher lifts so you would want more duration and lower lifts.

So in large part your heads determine optimal lift.

Another big factor in decision making is cost - high lift cams will require better valve trains.