I found a server group called Toxic Network and it is running two modpacks right now. One is Prominence II and the other is FTB StoneBlock 4.
The servers are very new and they want to open more servers later. They host from the EU but they say US players should still feel almost no lag difference.
Prominence II is on version 3.9.17 and StoneBlock 4 is on version 1.8.0.
