Best paywall for pay per view

Hi. I’m interested in creating paywalls for individual articles on my site – I.e. a pay per view system. I have seen a few different paywall options but wanted advice on reliable plug in options and which users felt was best.

Few things I think are key:

– ease for user. that is the hassle of clicking to pay and actually getting access to the content is almost zero.
– reliability. It cannot go down or be so slow as to put people off.
– simple set up. Easy to create paywalls and administer them.

Thanks!