I'm not an expert but I have throughly researched this. It is best to use a variety of feeder insects and really import to gutload them all regardless of their nutritional value. Crickets are a good staple feeder, they are easy to gutload.
Crickets are better than mealworms. I most heartily agree with Amanda that its important to provide variety. Dont rely soley on crickets, even well gutloaded ones.