Currently the W+ system with Paypal. But I also use a 3rd party script (wso pro guardian) that integrates into both for product delivery/tracking/security.
I use Warriorplus and JVZOO. JVZOO has tons of new features that really makes it easy to perform transactions and to set up funnels. As for Warriorplus, I covet the "WSO Of The Day" title that still eludes me
As far as where I live (Italy) is not possible to use an authorize.net account with JVZOO, I am currently trying to run my first business ever with Clickbank as it looks like the one to go since it also gives prospects the chance to pay by PayPal if you want to even though you don't have a PayPal account.
I use JVZoo linked to PayPal, Digital Access Pass and GetResponse.
We're having serious problems with GetResponse lately (both in terms of deliverability, and of contacts not being added to the lists, even direct buyers from JVZoo), so we're testing ActiveCampaign as a possible replacement, as DAP nicely integrates with it.
With these components, JVZoo + DAP as the affiliate / payment processors, DAP as the membership script and ActiveCampaign as the e-mail marketing system, we have all our needs covered.
BTW, ActiveCampaign has a nice "tagging" feature, akin to that of Infusionsoft etc.