Crocodile geckos are a native species here I had some as a kid and they were great. Very easy to take care of as far geckos go. In fact they were the first rept Ive bred. Its a shame that we cant have them anymore legaly (kind of stupid since they are really plentifull and I bet that 3 in every 4 people that find one in there houses would try to kill it before anything else and if we where allowed to have them that would change them from pests to pets)
As for cresteds they are even more pet like. This once rare New Caledonian species is a very inquisitive and friendly gecko. They will allow you to handle them once established (crocs inicialy are very timid but will also setle down and come sheck things out but they tend to remain very shy when you open the cage door, very rarely if ever allow to be petted and are prone to escape, babys tend to be less shy than adults)
Lets start by this, make your reserch (there are tons of care sheets) and put your doubts as they apear
In a nutshell, cresties are more handleable and get slightly larger than crocs, which are generally quite skittish. However, like others have said, both are very easy captives.