Obviously there are plenty of outfits out there, and tons of people who claim to do it well, but I'm not referring to fiverr gigs, or fly-by-night services.
I'm talking about reputable services you have used and who you've been happy with and delivered quality backlinks and quality outcomes to your sites PR in Google.
(Note: I'm not saying that Fiverr are not a reputable service, in fact, I use Fiverr for various things and have been very satisfied with the results)
In other words, quality service that truly made a difference.
Who do you recommend the most and why?
I'm not referring to hundreds or thousands of unrelated, irrelevant, haphazard backlinks, but pure quality and relevant backlinks. Perhaps better said, quality not quantity.
Bottom line: Who provided you the best backlink experience, and whose services rendered top quality results that actually made you money?