I always go back to mutt. It does one thing, read email, and it does it well.

The key is to set it up appropriately. Don't use mutt for downloading your email, especially if you wanna deal with IMAP. Use isync (mbsync) for that purpose (I used to use offlineimap, but it's buggy and not very fast).

There's also notmuch, which I use for indexing my email. It also contains a pretty good email reader.