I personally think that there are a lot of competitors trying to compete with ETH. 
One of my favorites used to be ADA with it's scientific approach. With it's peer review procedure they want to create a scalable, efficient and secure platform for dApps and smart contracts.
It has a quite similar idea as ETH, although Cardano was limited to about 1000 TPS, while SOL is way faster, not just the speed of transactions but also the block building.
As SOL is still in the early ages of development it has outdated ADA with a few things.
I think ADA still has great capabilities to catch up as it's development ist still not finished.
IMHO SOL and ADA are the most optimistic candidates to compete against ETH.
One of my favorites used to be ADA with it's scientific approach. With it's peer review procedure they want to create a scalable, efficient and secure platform for dApps and smart contracts.
It has a quite similar idea as ETH, although Cardano was limited to about 1000 TPS, while SOL is way faster, not just the speed of transactions but also the block building.
As SOL is still in the early ages of development it has outdated ADA with a few things.
I think ADA still has great capabilities to catch up as it's development ist still not finished.
IMHO SOL and ADA are the most optimistic candidates to compete against ETH.