I will say that, despite the Sky Peso moniker, Delta's FF program is actually pretty decent from my local airports when I just want to find a cheap economy route somewhere domestic or transatlantic. I don't have enough in OneWorld to compare there but from my hometown, it's loads better than trying to find Saver inventory on United. And there are maybe three places I'd want to go that end up being fewer points on WN than Skymiles on Delta because WN is rarely cheap out of local airports and dollar-based redemption and all.