There are too many coins with solid valuation today to name. This changes on a daily basis. Everything in crypto is dependent on time. That becomes the BIGGEST factor that receives the least amount of consideration. You can read thousands of white papers about thousands of coins and none of that really matters. At the end of the day, the success of a coin will be dependent on supply, demand, and TIME.
Just take a look at goods and services in this day and age. What is the hottest gadget? Who delivers the best services? Who provides the best content? You can name dozens of product, dozens of services, dozens of content providers. However, none of them will be around forever......
Crypto is exactly this. For some coins, like Bitcoin, they have endured hardships such as being considered the currency of the dark web. Time has passed since the early days and now it is the benchmark for all things crypto. Ethereum is an interesting coin but it isn't completely bulletproof and has had its share of ups and downs. Litecoin the same way.
This isn't 2013 anymore (or 2016, 2018, etc.) and as we move forward in this digital age where we will pay for goods and services that have value, I believe that security is going to be the most important characteristic of the coins that we choose to store in our wallets or spend. The old coins have paved the way for the new coins to fulfill the paths that were originally meant for them.
Overtaking ETH is easy. Just be a coin that can provide what ETH cannot. That becomes security and anonymity - the ultimate goal of all things crypto. Instantaneous peer-to-peer transactions for goods and services in without anyone else knowing 'who' or 'how much'. That's the coin that will win in the modern age and excel beyond the vulnerabilities of other coins.
That being said, I think that PIVX is an excellent coin with a tremendous amount of upside. It can transfer instantaneously and anonymously between wallets. Coins that can feature this type of trading potential and have extremely low or no transfer fees are going to become the new coins to have in your wallets.
There are also a number of other secure coins like Monero, Zcash, etc. that will become more valuable because their coding is stronger than just simply having a high hash-rate like Bitcoin.
In time, the transaction fees are going to hurt Bitcoin and Ethereum as it will cost the user more to move those currencies for simple everyday transactions. Even Litecoin will potentially face difficulties in being something that would be easy to use in everyday applications.
Litecoin, Ripple, Cardano - they are all just speculation. As the energy costs to mine the next blocks of Bitcoin and Ethereum grow, holders of those coins will need to reinvest in some sort of altcoin. Chances are, they will need to choose something that is secure, private, and won't cost a lot in fees to transfer.