If it's just for uploading files, I would (if you haven't already) seriously consider your options for just building it into the web app. Otherwise, I'd vote Q

If it's just for uploading files, I would (if you haven't already) seriously consider your options for just building it into the web app. Otherwise, I'd vote Qt/C++ as I've seen quite a few solid, fast apps built on this platform, though I'm not a C++ dev.