I think the most commonly used wallet is myetherwallet. Because the wallet is the easiest wallet to use. And I think it's safe enough if you use it carefully. You can also use a ledger wallet to store your altcoins. Choose what you think is easy and safe. I suggest you use ledger.
I also used myetherwallet and thought it was save, then there was a hack and many users lost everything. Then I decided to play it safe from now on and moved everything into a nano ledger wallet. It's quite unhandy though, I prefered the carefree times...