If IMAP is not a concern for you at this point check out Gyazmail http://gyazsquare.com/ It is made by a small developer and seems to be getting new features regularly. Its interface is nice, it's fast and cheap, $18. IMAP is on the upcoming features list. I have been using it since before the 1.0 release and think it's great. But I think e-mail clients are one of the more personal types of software. Each person likes their pick for their own reasons.