what is the perfect dev env desktop / distro for web devs ?

IMHO the perfect dev env desktop / distro for webdevs is any desktop OS of your choice PLUS virtualbox PLUS xubuntu OR linuxliteos

https://www.virtualbox.org/
https://xubuntu.org/
https://www.linuxliteos.com/ (also makes a great desktop for non devs)

BTW linuxliteos say they will make a BIG announcement on 14 jan 20 so watch this space

https://www.linuxliteos.com/forums/