Matic may consider for long term investing but you mentioned top coins ether, bnb, dot ada! I agree that those are best suggestions but Op already know about those and he wants to investing except those top coins because those are already grown a lot. That's why i suggested him "he cloud better consider Ftm & next" among the list of altcoins he mentioned as well as sandbox, cake & others
We can add several options to other altcoin choices but many investors stay on top coins for reasons of certainty of rising in the bullish period, because there is no guarantee that other altcoins can survive after the bear market passes and other factors due to the effect of the Luna crash so not many long-term investors believe coins other than BTC, ETH and BNB.
for safe reason with our investment , better give small alocation for coins outside top100 cmc. maybe some of us recognized these coins will give more profits than top cmc, but we also have to calculate about risk. our reason buying cryptocurrency coins was about earning money , so it should not be problem which altcoin we will buy as long as it could generate profits for us.