You are looking for long term partners that can work invisibly in the background and operate in a professional manner. If you choose to use mailing list a free service, have you worked out how they are making their money? Is it through compulsory advertisements or some other unprofessional method? Whatever it is, if you are not paying directly for the service, you will be paying by some other method.
Pay up front and be assured that they have an income stream which means their future should be assured. Once you have a system that does all of this, why do you need another process that duplicates all of this? Building an email list is just one mailing list element of your success, thus you want to keep it as simple as possible. Therefore choose the software that contains all the key elements and move onto what you want to do.
Remember the goal of internet marketing is to get out and do what you want to do, when you want to do it. Your goal is to escape the mailing list corporate 9-5 prison cell. If you have managed to find a single piece of software that does all of the above then you will not need and you must not use any other software.