If you want a suggestion because you don't want to spend time in analysis and get confuse, use
GetResponse. That is the one we use the most.
If you want to take the time to find out (this is the best approach), visit each one website, get familiar with their offers, sign up for their 14-day trial and work with their solution a little. You will get a feel for which ones you prefer depending on how you work, what are your needs and what you want it to do.