With PrimeDice you will always be guaranteed payment. With that being said all other services are obviously legit until proven otherwise. Whilst I like to keep up with competition, when newcomers offer increasingly higher rates with low levels of trust, I do not see this as viable.
Happy posting
GAW offers essentially 0.0016BTC per post (up to 50 posts) and GAW has proven to be reputable in shipping products and is using EvilPanda for the signature ad offer - who is reputable in doing these kind of things in the past for several other companies and doesn't conduct the offer unless he already has received funds from GAW to cover the cost for the first month - so using the "new" argument is disingenuous, IMO.
Just sayin'
Edit: So unless someone makes 134+ posts a month, then GAW is the better offer. But if they do post 134+ a month, then your offer is better.