oh well can you add this to the list It is a 2 chamber system which uses dual plutonium in the middle and uranium on the outside core areas it produces a good 140 eu for 5 hours and Is pretty cost effective except (for having to get 4 uu) here is the design.
I thought it was pretty efficient but thats up to you to decide.
edit randomly adding stuff to it you can output about 168 eu for 13 hours (though after 5 hours it goes down drastically so here is the system eu amount 168 eu for 2 hours= 124 eu for 3 hours = 5 eu for the net seven hours) instead of just 140 for 5 (same system applies after 2 hours it goes down to like 124 eu) this one uses 2 dual plutonium cells, 2 dual uranium cells, 1 uranium cell and 1 dual thorium cell. Here is the design again not as cheep but still a good design
also off topic why can we not see any ic machines in factorizations router