I wonder if it's possible to be better than a leather saddle (I'm only familiar with Brooks).

They're not overall perfect, but once formed to your body they are a perfect fit, if in exactly one position. Can any other material conform itself to your physique ?

A perfect fit is not necessarily comfortable, that depends on other things like leather tension, the ability of your body to receive the overall shape of the saddle and the sensitivity of the body parts involved. I've found that cushioned seats are more likely to cause pinching of my now old and thinner skin which can rapidly become a lesion if not addressed immediately. The firm smoothness of leather minimizes pinching (in that one perfect position).

The problem I have with my Brooks is that after several hours I start getting sore in that one best position and there aren't any alternative positions that are comfortable. The nose and rear of the saddle are hard as rock, so a lot worse than a padded saddle if you want to move around a bit for a break. Stopping and getting off the bike for five minutes helps a lot.