It probably depends whether you are using Android/iOs/other; may even depend on where your e-mail is hosted, if you are using one of the big freemail services.
KMail with pop3 works for me. It downloads only new messages to keep band-width low. All emails are stored locally so search and retrieve is very fast.
I was asking the same question not too long ago. I had also been using the built-in client, but now I use mymail.my.com.
You can use Pine
If it's mobile then you might have to deal with (i) lack of physical keyboard, so on-screen keyboard using valuable screen space and (ii) high latency and inability to navigate emails through dead/weak spots.