Hmm, this is actually a really close match-up.
EJ's rampage had multi-dimensional repercussions, he effortlessly destroyed/recreated the universe on a whim, he was portrayed as well above any other force(s) in the multiverse(inc. Spectre), and he very nearly succeeded in collapsing ALL universeS into a singularity. In fact, the damage EJ caused to the multiverse was so extensive that it took both Mxy AND Spectre 5 hours to fix it, which is remarkable.
The most we saw a single Beyonder do is destroy the entire Celestial race on a multiversal scale, and kill-off Eternity/Infinity.
Hard to say who wins here. If I had to pick, I'd probably side with EJ, though, primarily because the feats he displayed seem to be a bit greater than what we've seen from a Beyonder so far. I could definitely be swayed, though. /shrug
