Small Carrier Rockets: simple 56.5/m brick, from raws & self-proliferation. Dimensions: 124x79 With 16 on a planet, produces SCR ~900/m (and kills game's framerate on this planet). Power consumption: ~860MW (not counting 3x ILS).
P.S. Special thanks to the FactorioLab creators who make DSP late game accessible to the people like me.