I'd go for:
1. http://without-systemd.org/wiki/index.php/File:Negative-Galaxy-v1.5-SVG.svg
or a spinoff of this, seems sober and not too flashy, i like it
2. http://without-systemd.org/wiki/index.php/File:Devuan-D-Inspired-2.svg
if the swirl could be improved and, as a suggestion, the other letters
could be non-latin

Btw, is there a roadmap? Or is devuan just gonna be debian without systemd?