MyEtherwallet(MEW) call themselves the original etherium wallet, and a free, open source, client site toolthe wallet became so popular in space of few years, I couldn't find out specific reasons for that. But whatever it was, I just trusted them.
Creating account with them was very easy, as there are a lot of guides and tutorial videos on how to use it. Even without the guide, you will defiantly not get lost
Well didn't use it as my major wallet reason being that I love to have my assets in one place, I don't want divided attention. They only support ERC tokens. They have there private keys stored offline which makes it