I use Tokina 11-16 f2.8 Nikon mount for 3-4 years now with and without the Speed booster. By old zoom, you mean 7-14 f4? I think that after the speed booster introduction is a bit pointless. 2 stops slower and practically same FOV on wide end as Tokina (*with speed booster), and Tokina is a cinema-like zoom lens with internal focusing, people frequently cine-mod it and get a cheap fast workhorse of a zoom that works on many mounts, canon EF, nikon, mirrorless, (it even covers "full frame" nikon sensor at 16mm, I have tested it). So if you are not desperate about autofocus, and other electronic goodies, still seems like the best choice. For video of course.

I don't shoot resolution charts etc, in real life situations no problems in the corners, but I've also heard people complaining. Mine is ok.

I've put my money on the Voigtlander 10.5mm and at the moment is my favourite lens. Very well built, fast, sharp, takes filters and clickless aperture (if you need it). If you specifically need lens/speed booster combo, @inqb8tr is right on the money with the Tokina.

I have the 17.5 mm Voigtlander and the Olympus 7-14mm. Yet I am considering the 10.5mm Voigtlander because I want the faster lense with the great depth of field control. Why is the Voigtlander 10mm not a good fit for you. Lack of IS , autofocus, or other considerations? Appreciate your input. Thanks.

@DrLu I guess if I was going to buy a Voigtländer I would get one of the other sizes like the 25mm, but I don't need anything so fast, but I do need decent corners. I'm sure it's sharp stopped down,; Voigtländer makes amazing lenses. Also at this point to zoom is looking to add some flexibility although the Sammy 14 is kind of intriguing.
@Mickos thanks--and that is a gorgeous photo, by the way--did you try it on street scenes or landscapes?