My favorite email marketing tool would have to be GetResponse so we use it at our company(Isolated Marketing Nights) for email marketing. When it comes to pros and cons, I love the fact that it is very simple to use and it has a lot of specific features that I personally like. Their autoresponder feature is fabulous, as I currently have emails to be sent out automatically for over 150 days. I also like how they have a Perfect Timing setting for broadcasts, which allows your emails to be sent out at the best time for your specific subscribers to open.
In terms of cons, I would like it if there was more room for advanced features when it comes to sending autoresponder emails. For example, being able to send the previous email if it wasn't opened or clicked, or even adding tags to specific subscribers based upon actions they have taken. This is something that you can do with GetResponse, just not when it comes to autoresponder emails.
I highly recommend it if you're looking for email marketing software that is both simple and effective.