not a guru but I used to own the Omega SMP Seamaster Co-Axial.
Just got the Pelagos recently.
Both priced quite close with the Pelagos costing slightly more. Both using ETAs, the Omega with a Co-Axial escapement
Omega's pros- very accurate, more dressy than the Pelagos, gorgeous bracelet but very prone to scratches, makes you feel like Bond, a model that has evolved through many versions
Pelagos' pros- killer lume on both bezel and dial, looks more tool like, beautifully sculpted titanium case, bracelet and an expandable, very comfortable folding clasp, a totally new model
Pelagos far fewer owners.......
I prefer the Pelagos by far, no doubt...