From its ability to set up affiliate centers, order forms, and membership sites, integrate with Stripe and PayPal, Ontraport has it all. Yet, it is offered at a fair price making it a very good value for money, considering all you get in it.
But my favorite thing about Ontraport has to be their customer support- they probably have one of the best I have personally come across.
And they are constantly upgrading and up-leveling their system to support their users more efficiently.
Whatever system you decide to use, take the time to do some research and think about what core features you need and where you want the system to take you in the next couple of years. It will save you a lot of time and hassle in the long run.