I don't think you should base only on the opinion of the campaign participants. There are only a few rules for them. Number of posts they can/should write, payment rate and limitation in which boards it is desirable to be present or not. The Signature campaign serves the owner in building and promoting the business, and the brand and adapts to it.
It is best to contact one of the managers (why not more of them) and ask for specific suggestions based on their experiences. I noticed that Royse777 and icopress do some kind of analytics and monitor the final effect of the campaigns, so I believe they already have some conclusions about it.
Thank you for your advice. The first guy you mentioned we probably won't connect with as he has negative feedback and we don't like that in the campaign thread he also advertises his services. We spoke with the second one recently and he advised us to follow the trends of the forum, including current rates that will allow us to attract high-quality posters, so we will probably go with him.
That's what I received when Whirlwind management were very close to make a signature campaign deal with me :-D
They had this thought that the negative feedback left by JollyGood will effect their campaign so they decided to conduct it with someone else.
Anyway, icopress is also a good one to go with. Good luck.