Asking for the best online wallet to store your funds is like an ill person asking for the best faith healer... Sure, there are a couple faith healers out there that can comfort you in your last dying moments, but they won't be able to cure you, any betterment in your condition would be either coincidental or due to the placebo effect.

If you want a secure wallet that support multiple currencies, you can go for a trezor or ledger hardware wallet, or if you don't care about your security, there are a couple android wallets like coinomi or jaxx that will suit your needs.

As for your "faith healer" online wallet, there are wallets like Cryptonator out there, but if you use the search function, most of these multi altcoin online wallets have at least a couple running scam accusations against them. blockchain.info is indeed one of the most trusted online wallets, but they only support 2 coins, and i'm still not recomanding anybody to use them, since they remain an online wallet...