I couldnt agree more with the impaction comment. I never like mealworms, for one they do have the hard exoskeleton and further more, they tend to bury themselves under any substrate you use, eventually coming out as beatles that apparently are very bitter and not something the lizard will eat. It is really a pain to feed mealworms, the only benefit is you can keep them in the fridge for months.
I would deffinetly go with a leopard gecko if this lizard is intended for a child. They are very hardy, handling will not stress them out very much, and I have only heard great things from beginners that started with leopard's. I know I started with leopards 5 years ago, and it was a great dip into the reptile world.
I also agree that Crested Geckos are deffinetly an incredible lizard compared to leopards. They are highly addicting, come in a plethora of colors, hardy and eat less insects than leopards. The only thing I would be wary about is handling, especially for a child. These lizards tend to hop around and if the child gets scared it is easy to injure it. As well, they tend to lose their tails very easily if grabbed by a person/other animal. Bad part is it does not grow back, where as leopards do grow back. Crested geckos also require higher humidity and their tank set up can be slightly more involved.
Beardies are VERY high maintenence. They require very large enclosures, poop a lot and eat even more. You would be going through about 10 dozen crickets a week at the very least, feeding vegetables more often as they get older.
Comparing all three reptiles, I would definitely go with a leopard gecko. If you have any questions at all, give me a shout. I worked at a reptile zoo for a while so I am used to the questions
