SVG to EPS vector conversion full quality
inkscape -E out.eps in.svg
gives vector graphics conversion at full quality from the command line (no GUI).
Imagemagick doesn’t seem to be able to do this (Imagemagick makes gigantic raster EPS), but Inkscape does the vector SVG to EPS conversion well.
SVG to PNG raster conversion arbitrary quality
You can also convert SVG to PNG (raster) with
inkscape -e out.png in.svg
man inkscape for more options e.g. to select PNG resolution.