I hold the LTC and ETH mainly because of their proven track record. The haters gonna hate but there is no better alternative for the ETH blockchain. Creating a new one and applying the necessary things will take time which equals money.
Both LTC and ETH are tried-and-tested coins that have performed well over the years. Litecoin is one of the oldest, and best-performing cryptocurrencies in the Blockchain space today. It's second next to Bitcoin in terms of its limited supply of only 84 million coins that will ever be mined. Aside that, Litecoin has faster transaction speeds and lower fees than Bitcoin itself. With the recent announcement of integrating the "Mimblewimble" privacy protocol into Litecoin, I think it's a great long-term investment. The good thing about Litecoin is that it resembles Bitcoin in every way. Using the pioneer cryptocurrency's codebase, Litecoin will be able to remain resilient against attacks for years to come.
As for Ethereum, I believe that it's also a great-old coin to invest for the long term. It's close to being upgraded to PoS, which means greater performance and lower energy consumption. The Ethereum platform is the leader of the smart contracts space with ample support from developers and individuals worldwide. With Vitalik Buterin by its side, nothing can go wrong. Over the years, the Blockchain platform has been tested against external attacks and it has performed quite well to date.
Other good-old coins that are worth holding for a long time are Dogecoin and Monero. The former may not be active in development but it still has a large community supporting it. Not to mention, DOGE is traded on numerous exchanges in the crypto space. It's highly inexpensive, yet faster than Bitcoin in every way. You can use Dogecoin for tipping others or sending micropayments for services worldwide. And last but not least, we have Monero which is a tried-and-tested cryptocurrency that focuses on users' privacy than anything else. Transactions are hidden from the public by default, making it a great fungible cryptocurrency for daily payments. Despite the fact that there are other privacy coins which have somewhat-better tech than Monero (ZKPs), it's still the leader on the market.
Nonetheless, holding old coins is great because they're resilient against external attacks unlike newer cryptocurrencies of today. I tend to focus on few old coins that have made their reputation over the years. Those are Namecoin, Peercoin, and Primecoin. Each have their unique features and strong community support within the crypto space. Their prices may be still low, but that doesn't matter since their Blockchain networks are as strong as ever. What matters most is their usability and reliability than anything else. As long as you stick to good-old coins, you'll never experience undesired hacks (if you take the necessary precautions) like it's the case with newer coins like IOTA and NANO. Just my opinion