Given how morph driven the leopard gecko market is, I don't think this question has a single, succinct answer. It will vary based on a number of factors. The ability to temp-sex during incubation has made those factors a little less visible to the general public, but it's the same sorts of things that apply to any other species that is known for the genetic grab bag of colors and patterns.
I would say male especially if they are proven breeder males. It took me forever (a month maybe 2) to find a male gecko and I'm not even sure that this male is a breeder.
Like others have said, it depends. If someone is looking for a high quality male to go with females they have, it can be very hard to find one. Most of the breeder sites I go to seem to have about 90-95% females up for sale. I voted both because if you have some high quality males they usually sell pretty fast. But females seem to make up the bulk of sales.