When I'm running a pack with Dartcraft, force engines are usually my preferred method. If you're looking for an automated solution, then you need to consider both the fuel and the throttle.
For fuel, the two main options are either Liquid force, which is powerful (up to about 10 MJ/tick, with a milk throttle, I think), or fuel (less power, but more energy, runs at about 7.5MJ/tick for 600 000 ticks, rather than 60 000 that liquid force uses). Force is good, if you've got the supplies, fuel is useful for manually-filled engines, as it doesn't run out very quickly, but you do need to find oil wells to get it.
For a throttle, the main ones that I know of are water, milk and crushed ice. Water is obviously easy to set up (aqueous accumulator), but the lest effective (2x energy production). Milk is easy enough to do (rancher + cows), but needs to be transported to the site, I find that the power boost (x2.5 energy production) makes it worthwhile, even though it's more tricky to make. Crushed ice is tricky, as it requires bees. On the other hand, it's 4x boost would make it very valuable if you have the means.
Other than that, you're looking at either manually refuelling (cans + walking) or fluid teleportation methods (endertank/tesseracts). It is possible to put force gems straight into the engines, so you could filter those out of your quarry, into your engines, and use a water throttle, but that would be very inefficient (you'd lose the 1.5x quantity boost from squeezing the gemsEDIT: gems are worth 0.25 buckets directly, but squeeze to 1.5 buckets).
If I recall them properly, force engines' fuel is balanced with the combustion engine, with a water throttle, the values (as I remember them) are:
Fuels (no throttle)
Force: 4MJ/tick 60 000 ticks
Fuel: 4MJ/tick 600 000 ticks
Throttles:
Water: 2x energy production
Milk: 2.5x energy production
Crushed Ice: 4x energy production