Vasari Loyalists are cooler, just because they are Vasari... 
Besides they become a late game eco powerhouse when you swap out all those research labs (their caps count as labs with a tec) and you can destroy planets (if you want to). The VLT is fun with his teleport and his ship eating MAW (much like Unicron).
The VRT seems to be better overall due to the nice synergy of his abilities and the fact that you can only destroy him easily with lots of bombers otherwise he just keeps healing.