Only thing on Lizard Girl side is the AP difference (I suppose she scales to 28,02 tons, while Omega downscales to 25.77 tons, considering he said immediately after the feat that he would't be able to do it again)
Besides that the red guy has:
- Better skill (Around 7 years of militar experience, being the leader of a squad made of the best of the best, and fighting against multiple elite enemies at the same time in literally half of the series)
- Higher range
- Most likely higher LS (In Setsuna verse class M lifting strength is reserved to only a few, higher tier characters like 10% Deku)
- Multiple possibilities of trespassing Setsuna abilities (He could use his gauntlets to keep punching quickly and dispatch Lizard Girl pieces, the most effective way however would be to use the shockwave generator of the Arctic Empress, assuming he still have the abilities of his previous armors he could also use barriers and teleportation to avoid being hit).
- Finally, Omega would most likely used the same strategy he used against Kary: Make her use all of her energy thought time and finally give the final blow. As long as his armor could keep connected to the server he would have likely unlimited armor.
And as a bonus, in case she manage to damage him beyond salvation he could always use the Longinus Knife and explode himself, the range show in the end of Xionic Madness 3 is of multiple building, possibly multiple blocks.
So yeah, voting on Omega