What is the range of the lens you are currently using and that will give you a good idea what range you want as your next new lens - at least FIRST new lens since there will be more in your future.
The 16-35 F4 is at the wide angle end of the spectrum. If you like to think of things in terms of full frame equivalence then on your crop sensor camera it will have "reach and coverage" roughly equivalent to a 25-56 mm zoom mounted on a full frame.
I have a 17-40 F4 that isn't my least used lens but it is near that end of the spectrum for me because I don't use wide angle that much. For a general purpose lens, I find the 24-70 range to be extremely useful and if I were only carrying one lens it would likely be that lens or the 70-200 depending upon my photo plans for that day. I have both of these in F2.8 maximum aperture trim which pushes the price up a bit but Canon does have a F4 version of the 24-70 that is slightly less than the 16-35 you are looking at and many people really like the wide range 24-105 F4 that is in the same price range.
So, based upon what you are mostly photographing now and most want to photograph in the near future you can make the best decision which zoom range is going to be the most useful to you. And if you are interested in the wide range, decide if the 17-40 F4 will meet your needs because B&H is currently selling it with a steep discount for $499. I have been very happy with the performance of my 17-40 and would use it a lot more if I did more photography requiring moderately wide angle work.
Rodger
EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video
