It's hard to directly compare as it depends on where you will install it, other components etc.
For me, the RGB effect is the best on the TridentZ Royal while the Dominator Platinum - white or special edition, looks the best. The Vengeance feels like a cheaper product.
If I wanted to install it on any colorful rig or more silver/black theme, then I would pick TridentZ Royal. If I wanted to install it on black/white or any non-metallic, then I would pick Dominators.
There are also other brands and series but I don't know if you want great looking RAM at reasonable specs or something from the fastest series and the best looking RGB at the same time.