PDZ and UFO were on my shortlist too!
More silhouettes, an easy way to make a striking image:
北斗の拳 世紀末救世主伝説 SLPS-02993
Gorgeous low-poly game BTW.
ブレイヴフェンサー 武蔵伝 SLPS-01490
By coincidence, the inverse of the above.
DON’T PANIC! SEAMAN heh, heh T-39401M
I can’t find the disk alone in good resolution but looking confirmed similar designs for Seaman 2, the bonus disc, and even this (still?) undumped promotion disc.
Space Channel 5 HDR-0029 (in hindsight a poor choice of product code)
The PAL release isn’t bad either and arguably better for its simplicity. For some reason many Dreamcast games have entirely different disc art in each region and PAL got a lot of the best ones. Thankfully the DC does 60Hz VGA!