Samsung email. Pretty much a basic no-frills email app but works well using it for my Yahoo, Gmail and work's Exchange email. Gmail is not my primary email app and never was a fan of their email app or page so Samsung's basic layout and functionality works for me.
Have you tried Samsung focus? It’s on the App Store, a really good email app which has some really handy features such as being able to write memos and to do from the email and associate them together.
That’s increasingly becoming my default one over the stock mail which is excellent too (love the features where I can choose times my emails sync and when it stops syncing).