I "breed" Dubias but really I don't do anything, they do it all. I give em food and water crystals and it seems like every time I open the lid I have dozens of babies I never saw before. I only have a couple of adult breeding pairs, too.
Superworms are another species that seems very easy to breed. At least, I got a bunch of beetles I didn't even want or try to get. After that, I'm not sure because I uh... dispatched them, since I never wanted them to begin with.
I also accidentally bred Silkworms because I bought too much and fed them too fast when my chameleons were too small. I must have had hundreds of eggs, but I didn't refrigerate them and they still hadn't hatched in over a month, so I refrigerated them for a month, took some out and those never hatched. I think my refrigerated might be too cold. Actually I still have some refrigerated, but I don't expect anything out of them lol. I bought a huge bag of food for those damn eggs, too ... Maybe I'll get some eggs and try again.
I'd have to say the most difficult bug for me to breed by far has to be crickets! Everybody says they're easy, and with some methods I'm sure they are, but it was really a pain for me. The few eggs I could rescue from being eaten by the crickets hatched to tiny pinheads who ended up getting eaten by ants on my balcony.
All that being said, going forward I'm most likely going to breed Dubias and Silkworms because I think they're both at least reasonably easy to breed and make a great 1-2 combo nutritionally as staples for my chameleons.