Oh, there are quite of few of us here that have both. Honestly, you've covered the good starter cold blooded animals: leos, corn snakes, and bearded dragons. I tend not to suggest cresties to a first time owner for a few reasons, but let's start with your message and work those in:
FYI Cresties also have to be temperature controlled, in fact, we have found their tolerance range to be much less than leos. 85F is absolute max, they start getting stressed above 83 or so, you can let it drop to about 65F at night, but they will be more active if you can keep it in the low 70s.
Crested Gecko Diet (CGD) is really the best option, baby food has to be mixed in proper proportions and all the vitamins, it is just too much to mess up and get something wrong. Now as for crickets, I have found that little ones are best raised on a combination of crickets and CGD, the extra protein is of help. (Dust with a product like Leopard Gecko Dust from the same guys as CGD.) Now, crickets are completely an option. Even some breeders raise on CGD alone from baby to adult. But since I have crickets for my leo anyways for me it isn't a big deal. And really, even if you just pick up a few for a treat for the crestie one day, the look of surprise on her face is priceless. Mine gets this look like, "Whoa, I caught something... hmmm... I wonder if it is food?... Should I eat it?" Literally, she spends almost 30 seconds to a minute with the cricket hanging out of her mouth contemplating whether to finish it off. Pretty funny to watch.
IMHO, leos are easier to tame and handle for the beginner, you can see a post about this same thing between myself and Andrew a few threads down right here. (Something like why don't you want to be held? is the name of it) If you find the leo board (where we all post as well) you can find a good explanation of how to train a leo amazingly well by Olstyn... or maybe he could be begged to repost it here? Pretty please?
Also consider leos can climb, but can't stick to ceilings should one get away. Something to think about. Oh- that would be another thing to think about, you are looking at size of enclosure, some say leos can live just fine in a 10 gallon, I prefer what is called a 20 gallon long, but mine is spoiled. A crested would need something similar to a 20 gallon high.
OK, now let's talk about the one thing no one bothered to tell me about - poo. Leos pick a corner and it is super easy to clean. (BTW use paper towel substrate for both leos and cresteds for ease of cleaning and such, my opinion.) You remove that corner of paper towel, all nice and dried up and stuck and dispose. Easy. Now... cresteds... well, they go anywhere and everywhere, you have to clean the glass, the plants, the everything... and there is that possibility you may have to clean yourself as they don't have the manners that leos have.
So, I guess I am pretty strongly on the side of leos first, but cresteds as a fine second gecko. I would just be of the opinion that if your 8 year old wants to help, leos are much easier to hold with less overall training time. One of our leos loved computer games and would watch them for hours, our girl we have now loves TV and will sit on your hand for as long as the show is interesting.
Please feel free to ask as many questions as you want. We are more than happy to help you and really appreciate answering questions before you get the animal and so you can have everything set up a head of time. Also feel free to read some of the posts here and the leopard board, I know recently I posted my favorite crested care sheet somewhere and like I said, Andrew and I had a conversation about the differences between leo handling and crested handling.
Anyways, good luck, ask more, we'll do our best to help! Welcome!
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0.1 Albino Leo Gecko
0.1 Crested Gecko
1.0 Dear Boyfriend
Departed: Harvey and Spock
