In the case of "best office chair", the most valuable content is probably written by someone who's tried the product and is similar to you. I've had the most success finding those people hanging out in an obscure forum.
The SEO spam sites might do a good job reading the office chair's product page and wordsmithing something compelling, but often they haven't tried it at all. They're incentivized to sell something and that incentive leads to less value (in my opinion).
The SEO spam sites might do a good job reading the office chair's product page and wordsmithing something compelling, but often they haven't tried it at all. They're incentivized to sell something and that incentive leads to less value (in my opinion).