Any suggestions what I should use as substrate for lepord geckos?

Anywhere i look I get a tone of different answers. Rn I'm using reptile carpet, ik that's bad and that's why I'd like to change it but there is so many different options. I'm scared of impaction bc both my leos are used to repi carpet for nearly 3 years now. One is a rescue so maybe even longer? Will they eat the substrate more bc they are not used to it?