Cardano is one of the best coin for long term investment. In crypto market, there are many wallets for cardano like hardware wallet and online wallet. In those, hardware wallets are more popular and secure than online wallets. So, I prefer you the hardware wallets for cardano like Trezor, Ledger nanoX, Ledger nanoS etc. They are very strong wallets for Cardano and more secure than othan other wallets.