From my point of view the best wallet to hold alt coins is hardware wallet because hardware is very secure so you all should use hardware wallet if you want to hold any token for long term but many of us can't buy hardware wallet they even use Metamask and Trust wallet Both are safe for my opinion.
Personally I had used metamask and Trust wallet respectively both wallets are recommended to any crypto user, both wallets are user friendly and easily navigable, however it's better to avoiding hodling huge amount of coins in those online wallet because it can be compromised through phishing by hackers who had devised various sophiscated methods of stealing coins, best bet is to use to hardware wallet to hodl huge amount of coins afterall the cost of the hardware wallet is very affordable and it usefulness in securing those coins is unparalleled and incomparable with online wallets.