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....
...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...
THIS.
I think one needs to understand that there are no completely secure online wallets (because no system is 100% secure). It's best to keep only small amounts of BTC in online wallets (just so you can use it for small purchases), but when storing your "riches," nothing beats the security of an offline wallet-- a paper wallet, or use 'cold storage' (provided that you take extra precaution to keep them secure even from your family members).