The most widespread assets among staking providers are Cosmos, IRIS, Kava, and Tezos. Staking fee ranges from 0 to 50%. 0% fee provided by the Staking platform for staking Cosmos and Icon. While the highest fee (50%) is taken by InfStones for staking Aion.
Data was taken from Staking Rewards. Digital assets exchanges were not added to the list.