The thing about most types of power generation is that once you reach the stage where you rate your power in KRF/t, increasing your power output usually means "build more XXX generators", since all your generators are maxed out on upgrades. Also, power needs tend to increase exponentially up to a certain point, so usually it's not enough to build another generator now and then, you usually need to double their number now and then. Which is boring.
That's why I like Big Reactors. You just don't build another one if you need more power than an early type generates. You build different ones, with different layouts, different coolant types and going from passive to active. The only other way you can do something similar is with the condensed XU generators, which are useful but a little boring variants of "burn X for power", or with ReactorCraft reactors. Unfortunately, I'm sort of burnt out on Rotary/Reactorcraft - you can't shut the fusion reactor down and it takes an insanely overpowered canola farm to keep the HP turbine running. Building the thing was great, running it, not so much. So that's not an option for me, and currently I don't know what use I'd have for more than 100KRF anyway.
Also about Big Reactors, if you build a really big one and run it at low capacity, it's extremely fuel-efficient. You can probably get away with a small patch of Magical Crops plants to generate the yellorium you need. I'm going to test this in my current world.
As for power needs in general, it's hard to imagine a need for constant power that goes beyond around 20KRF/t. There are spikes in power requirements way higher than that, but usually that's for things you don't run constantly. Running the Infrastructure to run a ReactorCraft fusion reactor costs more, but then you'd have to ask yourself why you need the 50 GRF/t it makes.