Polkadot is currently the toughest competitor for ethereum compared to other platform blockchains like eos, stellar, waves, neo and it is actually very difficult for polkadot to become ethereum killer considering ethereum still has advantages over this, but if ethereum makes a mistake it's not impossible polkadot will become ethereum killer.
So I'm hearing from that ultimately ethereum is the only one that can engrave itself and sort of give out the lead to competitors.
Otherwise, there is no such company to really compete with ethereum on its current level