This has been a debate for as long as I've been a UX designer (mid '90s), and probably much longer. Ultimately, the answer about this UX style is very much the same as a question about writing style—there's no objectively right answer, but you have to be consistent. For example, you can pick up any number of style books from Strunk & White to the Chicago Manual of Style and get different "right" answers about writing…
> So the answer from this veteran UX designer would be: Use whichever placement your users are going to be the most familiar with, but whichever you choose, be 100% consistent with the choice you make. Not only that, but make the "OK" choice standout with a different color. If the "default" option is brighter than the rest, your eyes will most likely gravitate towards it first, regardless of the order of the buttons.
It's a terrible web app.