there aren't a lot of cons if you have the time for these guys, I would have to say in my openion that a leopard gecko would be a little easier to care and has less worries. Cons,Crested geckos: with a crestie you have to worry about dropping tails a little bit more, you have to mist them, worry about over/under misting, And if over mist can get mites a little easier than a leopard gecko. Pros, Cresties: they are just about the easiest gecko to care for, really fun to handle (from what I've heard), look awesome!, have really cool sticky feet, can be handled, sleep with there eyes open, live on average about 10-15 years, a single crestie can live in a 15 gal. tank, and are very easy to bread. Cons, leopard geckos: will starve them selfs if they feel something is really is wrong, your not supposed to use sand (I use it and my leo is fine), if you get certain kinds of leopard geckos they can be a little mean, if they lose they're tail it grows back look'n kinda funky, sometimes don't eat if they feel something is wrong. Pros, leopard geckos: easy to care for, like being handled when adults, awesome to handle!, if givin proper care can live well over 10-15 years, easy to breed, very inexpensive to keep, very simple care, and don't have sticky (so you don't have to get the broom out every time he trys to crawl on the ceiling)
don't get me wrong i do like cresties and am working on getting one. these two geckos are on the top five easiest to care for reptile poll that tells you how easy stuff is chart! i think that both of these geckos are an awesome choice, its really up to you and what you like.
Good luck!