Investing in top coins are the safest way in my opium.
Ethereum has proven to be a solid coin and therefor a good choice for long term investing.
Indeed, eth is one of the best alts to invest nowadays.
If you are not a fan of diversifying then choose eth and bitcoin. These coins are well-established and has many supporters thus even the market turns bearish for sure these coins can bounce back and can reach another ath though it wont happen in snap. Thats why we need patience because we dont know when it will going to happen.
I don't have much time to research new coins because I still have a lot of work to do, so in the investment, Bitcoin and Ethereum are enough because these two investments still bring good profits for me. For the past two years, I have chosen this traditional investment because these two coins are easy to trade if you have the knowledge, and if long-term investment is definitely a good choice.