I'm fairly pleased with the steam, magmatic, and compression dynamos so far. Very compact and even though liquefacted coal is less efficient or whatever than BC fuel or doing stuff with steam boilers, I've found it very simple and compact to set up and basically resolve my mid-game power requirements.
and never mind being less efficient, the compression dynamos are still waaaay more efficient than the coal power dynamos and that's fine with me. I have 5 set up, supplied by an ender chest that I keep filled with coal when I mine (with an ender pouch), which is emptied by a thaumcraft golem into a pulverizer hooked into a magma furnace or whatever it's called. Even though it idles they and a few magmatic dynamos are more than enough power for the fuel they use to process a good hour or two of caving.
I'm debating whether or not I'll set up some reactant dynamos. The fact they can use sugar as the reactant and they can take sewage or seed oil as fuel is pretty interesting to me. Pretty amused that I found a youtube vid describing it as "the poop engine"
edit: further on the reactant dynamo, I don't even care that sugar + sewage is a pretty puny amount of RF compared to other fuels or dynamos. I know I'll have fun making the infrastructure alone to be perfectly honest, and I really like having low maintenance renewable power as a backup.