I am a user of Aweber and Getresponse for many years, they are quite good as all my mailing list are stored inside them. With the recent launch of ConvertKit, I am impressed with them and decide to move over.
These are the 5 reasons why I move :
1. It is cool to be with them
2. No more more bill with duplicate subscribers
3. The interface is quite cool
4. I love the price plan
5. We got to move on to find new solutions.
If you love what i am doing, you can always join the convertkit here