Going to be honest here in my personal comic cosmology, cosmic power is measured in Kirby Dots. Slight bias...
An interesting point in that we don't really know in what way the ring was used. One might assume that the GLC battery might be considered the higher level of technology, as it was the target of Granny Goodness. Now that I'm thinking about it, we've really not seen all that much of mother boxes in terms of raw power compared to GL rings. The reason being that for most of the corps, the ring is the whole of their superpower, while the New Gods are using mother boxes as, well, "fancy god ipods."
I'm still leaning towards mother boxes as the more sophisticated tech, since they seem to contain a metaphysical or spiritual aspect to them, and pull off feats that I've never seen out of a ring (Boom Tubes being the big one, also healing.)
Now, if we gave Himon, creator of the motherbox, a GL ring, would he be able to re-create the motherbox? Didn't Scott Free get his soul transferred into a GLC ring via motherbox in the sequel to The Nail? Crossover questions are starting to muck up my thoughts.