Clickfunnels is the most popular all-in-one marketing funnels tool. Besides well crafted landing pages it lets you create membership sites, order forms, one-click upsells, affiliate centers, automated webinars and more.
Because there's so much you can do with it, Clickfunnels can be a bit overwhelming at first and some of the integrations have been a little buggy at times.
Plans start at $97/month for 20 funnels, 100 pages and 20k visitors. There's a 14 days free trial available, but a credit card is needed.