Vader has better Force feats in a direct contrasting between the two, but power-scaling would still tip the scales in Sidious' favor.
Dueling, however, isn't nearly as close. Toying with Maul and Savage - vastly outstrips anything Vader has done with a blade.
Palpatine wins handily. Unless, we decide to nitpick about Legends having far superior speed to canon, or something analogous to that line of reasoning.
Originally posted by The Ellimist
How does powerscaling favor Sidious? He's powerscaled off of canon characters, none except for Vader of which have any impressive feats.
Vader's feats [casually collapsing AT-AT, bringing down ships, and exploding/pulverizing Lyleks] and Dooku Orbalisk showing.
Lyleks hide, in particular, is sufficient enough to deflect blaster bolts, whose plasma discharges have insane showings of damage output in canon. Numerous times throughout TCW show we see blaster bolts utterly pulverizing thick rock structures, and even collapsing support beams sturdy enough to support enormous Geonosish caves (See The Clones Wars S2Ep7). So clearly what Vader did to them is pretty freaking impressive, and Palpatine is far above that.