F/2.8 is great to have throughout the zoomrange for portraits, for landscapes this isn't really necessary. Generally one wants to stop down for landscapes, to get as much in focus as possible.
OTOH, you could also use the 50 F/1.4 for portraits, so it is a bit of a moot point, unless you shoot a lot in low light. However, I personally find that even F/2.8 often is too slow in that case, although IS compensates a lot for that.
You also need to consider that with portraits, if you plan to have faces sharp in focus from the tip of the nose to the ear lobes in head and shoulder shots, you generally need at least F/4 to achieve that. So, unless you plan to do that most of the time, it doesn't matter which lens you would choose. The 15-85 will give you more flexibility in zoom length, the 17-55 more flexibility in aperture.
Personally, I'd take aperture over FL in these cases. I do find that F/5.6 at the long end for a relatively short lens is a bit dim, and also obstructs me in the creativity that a larger aperture provides.
Furthermore, if you do plan on keeping the 10-22, I'd seriously consider the 24-70 F/2.8L. Slightly longer, therefore better for portraits then the 17-55, and the lower end is covered by the 10-22. The difference between 70 and 100 (100-400) is negligible IMO, as is the difference between 85 and 100.
HTH, kind regards, Wim
OTOH, you could also use the 50 F/1.4 for portraits, so it is a bit of a moot point, unless you shoot a lot in low light. However, I personally find that even F/2.8 often is too slow in that case, although IS compensates a lot for that.
You also need to consider that with portraits, if you plan to have faces sharp in focus from the tip of the nose to the ear lobes in head and shoulder shots, you generally need at least F/4 to achieve that. So, unless you plan to do that most of the time, it doesn't matter which lens you would choose. The 15-85 will give you more flexibility in zoom length, the 17-55 more flexibility in aperture.
Personally, I'd take aperture over FL in these cases. I do find that F/5.6 at the long end for a relatively short lens is a bit dim, and also obstructs me in the creativity that a larger aperture provides.
Furthermore, if you do plan on keeping the 10-22, I'd seriously consider the 24-70 F/2.8L. Slightly longer, therefore better for portraits then the 17-55, and the lower end is covered by the 10-22. The difference between 70 and 100 (100-400) is negligible IMO, as is the difference between 85 and 100.
HTH, kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....
