This nutritional chart [link] was written for newts and stuff, but it does show about the same info we need to know. Personally I prefer nightcrawlers as well, because there's less chance of impaction and the calcium content is way higher than adult crickets. I also supplement with small chunks of frozen fish and shrimp, and the occasional (monthly, at most) pinkie or fuzzy mouse. Some choose to feed adult mice, but I find that they make the frogs sluggish and swollen looking.