Although its been over a year since i was high lvl, id have to say the Secret forces rifle. Its capacity is high, the fire rate is good, and its damage is on par with the hell raiser. It cost like 200 gems nowadays.
I have it, but I prefer exalabor
Anti ch rifle
Or ch merecany
Really any champion weapons. They are the only weapons that don't cost parts that can be upgraded to max efficiency (75). Most of all, Champion Peacemaker, but that just because I like the new feel of the miniguns and I have a fondness for the Automatic Peacemaker (I was playing back when it was one of the best primaries IMO, and used it all the time).
I will think about it
Eye of Ra or the champion weapons
What do you think?