I'm using a Chaos Gem with Flight, Capacity 4 and Recharge 4, which works wonderfully, lasts a long time and recharges pretty fast. Hopefully I'll eventually find an Everlasting Abilities totem with Flight, though, because it would be nice not to have to ever worry about running out of power.
Incidentally, I'm surprised that the Youtuber's I've watched play haven't been using Industrial Foregoing's Resourceful Furnace. It smelts 3 things at once, is reasonably fast (it takes 39 ticks to smelt 3 items when upgraded) and produces Essence. I've been making Fluxed Phyto-Gro, and my automation for that has produced something like 100 buckets of Essence in just a couple of hours. Seems like a nice additional source for Mob Spawning.
I'm also tempted to make a second ET Void Ore Miner. It's taking forever to get the stuff I need to upgrade to a tier 2, and since I want to have 1 of each miner, the only real waste would be the controller block.
Edit: Word of warning to anyone making the Angel of Vengeance statue thing. It will delete everything in an 11 X 11 area centered on the middle of the structure (don't know how tall). It deleted my elevator and part of my phyto-gro set up when I made it...also, it sets you on fire with lighting. Sigh.