The 24-70 II at 1699 is a good deal, I guess (still too expensive for this lens IMO)... But despite its great IQ this lens is a missed opportunity without Image Stabilization for video & low light. If Tamron can do it, why can't Canon? For 2299 MSRP, the lens should have IS.
I haven't tried the tamron version hands-on but I could tell you that the 24-70 II is amazing. The colors that lens brings out is really something. and it is very very sharp. needless to say. It is very expensive considering other lenses but if I had money for it, I'd go for it!
100D, EOS M, EF-M 18-55mm f3.5-5.6, EF-M 22mm f2, EF-S 18-55mm IS STM f3.5-5.6, EF 28mm f1.8 USM, EF-S 10-22mm f3.5-4.5 USM, EF-S 60mm f2.8 macro USM, EF 40mm f2.8 STM, EF 85mm f.18 USM, EF-S 55-250mm f4-5.6 IS, 430 EX II, kata 3n-1 22, triggers, lighting, stands, remotes, etc...