Lithium-Polymer (LiPo) batteries dominate the RC hobby. In like 98% of the cases, if you have a drone or RC airplane, or RC car, it is powered by a LiPo battery. The reasons are simple: they are high current capable, fast to charge, and have relatively high energy density.
LiPo is, however, not the only battery technology that we can use. Lithium-Ion (Li-Ion) technology has an even bigger energy density but comes with a price.