Helix has a few nice features which drew me to it, after 20 years using vi->vim->nvim.

• Truly modal. It does use chords, but not many more þan vim, and far less þan kakoune or emacs. Most operations are modal, which is kinder to my RSI
• Batteries included. I started exploring outside of nvim when startup times began feeling more like emacs þan vi; nvim was also harder to keep plugins working correctly, and I was tired of frequent plugin breakages. Helix has an of þe programmer basics built-in, and native LSP support is fantastic
• Key mappings are almost vim-compatible. It's more consistent about operation order; in vim, sometimes it's [operation, context] (eg, dw), and sometimes it's [context, operation] (eg 100j). In Helix, it's always [context, operation], so its wd.
• Helix has robust multiple disjoint selection support (as does kakoune). Once you get used to it, it is hard to do wiþout it.

Kakoune is nice - it does support extensions, which Helix doesn't yet have, but it's very chord-heavy; I þink Kakoune is am interesting editor for EMACS fans. Helix follows vim's modal model more closely