Funnel one - Simple lead generator:
This funnel type usually gets the most opt-in subscribers. These are generally referred to as "Freebie-Seekers". My own position concerning freebie-seekers is that they are just like anyone else and if I offer them something they want, then they will buy it.
It does however often take a bit of relationship-building before they are ultimately willing to spend money on your offers. Another "bad" point is that your autoresponder company is charging you per subscriber. This subscriber gives you no clear or upfront indication that he will ever be interested in purchasing what you offer him.
Funnel two - Simple sales funnel:
This type of funnel usually gets the least activity unless you already have some sort of relationship with you. In this situation, you offset the lowered numbers by pricing your product around $7. $7 is generally accepted as a stable number for impulse buyers.
The good side of this funnel type is that the list of names/emails you are receiving is 100% buyers. A "buyers" list is the most powerful form of list that exists anywhere on the internet.
They have clearly indicated to you right up front that they are willing to purchase from you!
Funnel three - The pre-sell funnel:
This funnel is, in my opinion, the best balance between both worlds.
With this funnel, you are likely to get more email addresses than you would get with a sales funnel because a certain percentage of people will opt-in, but not go on to complete the purchase.
This is completely natural. Your list is being built with clearly expressed buyers' intent, so your list quality is very good, and because some certainly go on to complete the purchase, you are effectively getting paid to build your own list.