I own a Breguet 5707 and a Richard Lange.
I find that the finishing on both watches to be top quality but the Richard Lange is the more accurate of the two. However, I must add the comparison for accuracy is a bit unfair since they are different watches designed for different functions.
While there's no denying that Breguet watches are aesthetically beautiful, I must confess that I had trouble reading time on my watch. The hands are a little too thin for good legibility. In this regard, I find Lange watches (not just the RL) to be easier on the eye.
Have you considered the new Lange 1815? I think it's in the similar price range.
Regards,
iAn