Best can be a relative term depending on how you process and what you need out of it.
I have used DPP for years, and still think it does the best for solo images.
I bought LR 4 several months ago, I like the work flow. I like the way it does noise reduction. I am still not convinced that if I pixel peep that it does a better job than DPP. But I like the speed that I can process with it.
I haven't tried DxO in a few years, but some people like it. I wasn’t impressed with it, but it may have gotten better.

You have LR and DPP, DxO offers a free trial. Why not take test images and in each program do samples of the test images in each program to the best of your ability, compare and whichever is best go with it. I think all three versions might vary from person to person depending on their level of skill and how well they can use each program. After all, it isn’t important how well each performs for me; it’s how well they perform for you.