By paid promotion do you mean "commission", "flat fee" or both? Personally I wouldn't pay anyone a flat fee, but I'd pay a decent commission of say up to 25% if only the broker/seller has a decent sell through rate.
With regards to what's more valuable, it depends. Having been self employed all my life, at least for me, I'd say a "2-word meaningful domain is more valuable. Much of it depends on a multitude of variables surrounding the domain. I happen to be very familiar with the healthcare industry, the financial services industry, the real estate industry and sports and entertainment. Recently I hand registered a domain TossUpSports.com that I plan on introducing it to both the "Sports World" and the "Gambling World" Personally i believe it has a lot of value for a lot of reasons. Few traditional domainers will see in it what I see in it but few domainers have the sort of experience that I have.
Good Luck