gmail, by so many orders of magnitude.. Email interface designed by people who seemingly have never tried to read email.
Threading is completely broken, filtering is broken, compose screen is unusable.
At previous companies I've had to use gmail but was able to use a sane email client via IMAP so it was almost ok (although still somewhat broken as gmail doesn't handle IMAP correctly). At current work they disable all access except via the unusable gmail web interface. So definitely gmail is the worst I have to put up with everyday.
jira would be a distant second, but no comparison.
Gmail was so groundbreaking when it first came out in 2004. AJAX was barely a thing, and Gmail used it in spades everywhere. I remember it being mindblowing when you didn't have to wait for full page refreshes for simple actions.
My problem is that it's remained frozen in time for years. Yeah, they tweak the visual design every few years. But so many other email clients have far surpassed it, and they've done nothing. Other than create Google Inbox. Which was amazing. And then Google shut it down. ️
My main gripe with Gmail is how often it will take upwards of 20 seconds to delete/move/spam an email, evidenced by the tab complaining if I go to close it. It's an incredibly common issue and doesn't seem to be directly tied to the quality of my internet connection.
I've been using email since 1985. For me, gmail remains one of the best email experiences I've ever had. My only gripe would be the psuedo-enforcement of top-posting.
Threading is completely broken, filtering is broken, compose screen is unusable.
At previous companies I've had to use gmail but was able to use a sane email client via IMAP so it was almost ok (although still somewhat broken as gmail doesn't handle IMAP correctly). At current work they disable all access except via the unusable gmail web interface. So definitely gmail is the worst I have to put up with everyday.
jira would be a distant second, but no comparison.