I really wish there was a standard pixel format for terminals that was better than sixel. iTerm2 and kitty each have their own custom mechanism, but AFAIK, they are the only ones that use their respective protocols.
It's very actively maintained by someone who cares a lot about features and user experience. In fact I've switched to wezterm right after a current Alacritty maintainer rejected my little pull request that excluded fancy newline signs and stuff from the default URL characters list.
Aside from cool features, the renderer is better too, IIUC it's already using lots-of-quads like a proposed alacritty improvement in a long unmerged PR.