Pro to precast: it is a strong material but limited in colors and finishes.
Con to precast: Sometimes the measurements they take are wrong and the coping doesn't end up looking professional.
Pro to poured in place: 2 options to the coping edge (bullnose or square edge). Many more color and finish options. If you do banding throughout the yard you can pour the same color to match everything.

We always install poured in place coping unless the customer wants Travertine or Limestone coping. I hope this helps. Here is a poured in place pool picture in Malibu, CA.

NOTE: if you install a salt system then precast is probably better. Salt eats away the cement in poured in place much faster and exposes the aggregates.