The first beta of Ubuntu's upcoming 17.04 Zesty Zapus is available for testing today. As usual, the official Ubuntu flavors and Ubuntu MATE have not been released yet, but the following ISOs are currently available for testing:
Kubuntu, Lubuntu, Ubuntu Budgie, Ubuntu GNOME, Ubuntu Kylin (does not concern you because it is Chinese Ubuntu), Ubuntu Studio and Xubuntu.
Kubuntu was the first to officially publish the release, saying:
"Today the Kubuntu team is pleased to announce that Kubuntu Zesty Zapus (17.04) beta 1 has just been released. With this beta 1, you can see and try out what we're preparing for 17.04, which will be released in April
Note: As the first beta of Kubuntu and Ubuntu in general it is not recommended for novice users or environments work. Anyone who needs a stable system better wait a little longer.
Interested beta testers can download beta ISO from the following links:
kubuntu-17.04-beta1-desktop-amd64.iso (1,661MB, SHA256, signature, torrent sites)
lubuntu-17.04-beta1-desktop-amd64.iso (906MB, SHA256, signature, torrent sites)
ubuntu-budgie-17.04-beta1-desktop-amd64.iso (1,534MB, SHA256, signature, torrent sites)
ubuntu-gnome-17.04-beta1-desktop-amd64.iso (1,432MB, SHA256, signature, torrent sites)
ubuntukylin-17.04-beta1-desktop-amd64.iso (1,566MB, SHA256, signature, torrent sites)
ubuntustudio-17.04-beta1-dvd-amd64.iso (2,973MB, SHA256, signature, torrent sites)
xubuntu-17.04-beta1-desktop-amd64.iso (1,280MB, SHA256, signature, torrent sites)