[drdec]

To me, the killer feature of Unity was the searchable application menus. Wish that was still a thing

[fao_]

KDE supports this! It's called the "global menu", and has search built in. GTK app support is iffy, though

[dualogy]

Since I found with searchable app menus / start menus that I don't ever navigate through menus but just start typing, I ditched the menu entirely and have KRunner bound to the Win key. Not only is it fine with any desktop app GTK or not (that packagers have ensured will install with its FreeDesktop metadata file or some such), it supports all the enabled KDE Search plugins. So I don't ever open a calc app again, either..

[Qem]

In Ubuntu MATE there's a mode that sort of emulates Unity.

[blauditore]

Same here! Never found a replacement for it in Gnome Shell.