As long as the site has an honest and informative free tour and had quality content with regular updates I would go for revshare no trial. They are the only ones worth promoting IMO.
If you set a 1 day trial it is easy to forget to cancel and then you might feel cheated that it rebilled automatically before you did cancel it. This surfer could be lost forever to adult sites, or certainly to that paysite and maybe the referring site too as he won't trust it any more.
If I had to choose a trial I would take the longest as it seems fairest to the surfer (if it has automatic rebill at trial end).
