My general feeling about Capture One Pro is that it is - by far - still the best product on the market in terms of doing bulk raw processing of large amounts of images. It is fast and efficient. Workflow with Pro makes my job possible - or else, I would probably shoot .jpg files. During a wedding, I will often shoot 1,000+ images. Just chunking through the raw files is a huge part of the post production work. I feel that Capture One makes it happen.
Oddly, I don't feel that Capture One produces the best image necessarily of the different converters available...only that it is the best balance between fast work and a very good, usable image. If I were only doing a couple of images at a time, Capture One Pro would not be the way to go. Since I have learned about DxO optics (and looking forward to version 5), I have been so amazed by the great looking files that come out of it. Clean and perfectly sharp. The fact that the program corrects for lens aberration is a big deal to me.
I DO look forward to seeing what the new version of Capture One Pro looks like. Honestly, they are late to the game, and other companies are now making good quality products.
James