Vos proved to be vastly superior to Ventress, who can easily uproot trees with a gesture, and slow the fall of her ship, The Banshee. Not to mention he did beat Dooku in a saber duel, and overpower him via physical strength. Other than force augmentation, I don't remember if Vos had a force advantage in it's offensive applications such as TK.
That said, Vader wins. He muses being more powerful than Anakin--who has consistently matched Dooku in duels and powerful enough that Dooku's own power only gave Dooku an edge vs being "throw around like a toy--with the gap between him and Anakin being pretty large, IIRC. Plus that, Vader's armor can withstand saber strikes and having two small imperial walkers collide on top of him unscathed, two walkers that he casually levitated off of him seconds later. When being hunted by Twilek freedom fighters, Vader pulled one of their freighters from the sky. The book referred to these freighters as "big ships," so I'm assuming they were bigger than the average ones, but of course another interpretation could be that they were called big ships because freighters are larger than shuttles or tie fighters, etc; regardless, the interior of freighters are very spacious and are as big as small apartments, and can house several people comfortably, having bed rooms and such (well the disk shaped ones anyway, which is how the twilek freighters were described). Also, Vader, while in mid-flight, targeting and tearing open three vulture droids with one single gesture, while they too were in mid-flight, is not only a display of raw TK but a very precise and refined use of it. Then with one handed force pushes, we had him shattering lyleks--huge creatures with shells capable of shrugging off blaster bolts (see Obi Wan vs gutkurrs on youtube to see just how good their resistance to blaster bolts are and durability since they have comparable armor/shells). In one of the new canon comics, Vader casually lifted the front part of an AT-AT walker, while simultaneously ripping it apart, Magneto style. Vader's physical strength is such that with one arm he lifted the queen lylek (who towers over the other lyleks), and gripped both of Kanan's arms, disarming Kanan and sending him flying, rendering him unconscious.
As far as pure lightsaber ability, Vos's advantages over Dooku seemed to be his physicality. It's said Vos was unpredictable, but in terms of what? Pacing? Pretty vague term the author threw in there, and one hard to use as an advantage in these type of discussions, unless one is a master of multiple forms and can switch, or even a variety of other martial arts that can be used in conjunction with saber dueling. But that wasn't the case with Vos, as far as I'm concerned, the only thing that changed was his physicality upon getting stronger, everything he knew came from his experience as a jedi and his retraining under Ventress as a dark sider, which, oddly, Dooku capitalized on only after Vos opened his mouth and mentioned it. Dooku should have recognized it after a long exchange. So, yeah, that's my stance on the term "unpredictable" being used as an argument, unless it's explained. For instance, Savage can be labeled as being unpredictable here due to his unusual strength. I just see that term being used here just because the word was used in a book as if it can't be applied the other way around.
BTW, I'm obviously only referring to their canon feats for this thread. Vader's a beast already, with even more to come, huh Cart? Why is he so scared of anal head? Lol, jk.