If you set up a process correctly, then mekanism is the best for certain ores (Allowing a 3x output per ore to dust).
These would include:
Iron, Gold, Tin, Copper, Silver, Osmium.
The process you use is as follows:
Purification Chamber -> Crusher -> Enrichment Chamber
The downside to this is that the Purification Chamber requires flint to work.
The upside is that all these machines can be upgraded on their speed, allowing quick breakdowns. When coupled with the Ender Chest/Ender Pouch, and set up correctly on a AE network, these ores can be set up to auto-breakdown to dusts while you are out mining. Just install a chunk loader (Dimensional Anchor) where your base is to keep the machines loaded to do their work.