Wow, River is getting more love than I expected! No valid reasons given, but his name is poppin up big-time. Something about his thread put me off a little, he didn't seem to be very responsive to complaints but maybe he did it by PM, IDK.
I usually use river + amit + ewandy for all my homepages and then use amit for my innerpages, although I think I'm going to switch to using river for my inner pages as well.
Rivers service on its own can produce fantastic results for even the hardest of keywords, not only that he backs it up with advice, shares tips and SEO chat which is worth more than the price of the service.
Red Virus provides great service too and his links are best used to fine tune existing rankings or on less competitive terms.
Use both not either/or. Put simply if they were both women I would be smashing both of them at the same time.
River's works best for me too. Just ordered 100 bulk which were all completed astonishingly quickly and results were amazing. By far the best ROI available on any service on WF. Just make sure you keep the links flowing after the blast from web2.0s etc as this can prevent any drops a few weeks later.
Hmmm...this is interesting...Amit is typically my go to guy, but I may hit up some of the others that were repeated multiple times here...just like anything in internet marketing...test, test, test till you find something that works for you...