I had the Tamron 17-50 f2.6 VC APS-C and it had decent image quality, but the mechanics SUCKED big time. The focus throw was only a meager 45 degrees and very loose which made manual focus not very good for video.
The Canon 17-55 f2.8 is much better, but costs 2x as much.
If Tamron made it with decent mechanics and a good picture quality, I would be it because of the V.C. which is great for video.