Go tilt shift! Or at least be prepared to correct in post if not, at the cost of resolution and how precise you can get your composition. For professional work you really need the 17mm and 24mm at LEAST if you want to compete, imo.
The 17-40mm is okay... Soft at the edges particularly at 17mm, but not unusable. Better stopped down but never great. Performance improves as zoomed in; so does distortion, which is an issue but not terrible at 17mm. Weirdly, I like the bokeh with this lens. It's not smooth, but it's not yucky either, not that you'll often get much sufficient out of focus for it to really matter.
The 14mm Samyang is an odd one. Seems plenty sharp, but the distortion is very bad. If you don't mind correcting it in post (both for mustache and barrel, which makes it feel less wide in a bad way) it's good, plus if you want to correct for converging parallels I guess that can be part of the same process. But the 14mm L is a lot less distorted, for instance, and even the 17-40mm L is way better.