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InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
-HBM's Nuclear Tech Mod (Pretty big, tons of Reactors, high-tech machines, features, etc)
-IndustrialCraft2 (all its features, there's a reason why it is still a big one, i would suggest you to combine IC2, BuildCraft, Railcraft and Forestry (and addons like Binnines and GregTech Experimental (Download Link)) for a better experience)
NOTE:
The number of mentions on this list indicates mentions on common posts plus user suggested alternatives.
Hence, a higher number means a more popular project.