what can I advise what I personally use, it's Aweber for it's easy to use. I 'm completely satisfied with it and never had any serious issues.
The two main ones if you are just getting started are Aweber and Getresponse. I have personally never used Getresponse but from my understanding you are able to build squeeze pages from within the platform which you can't do with Aweber.
I don't think there's a lot of difference between the two, I know people that have switched from Getresponse to Aweber and vice versa and everyone will have different opinions.
It's a case of taking the free trial and using it to see how you get on and make a decision from there.
If you do decide to try a different one from the ones I suggested then make sure you use a paid platform not a free one. Free ones have been known to be unreliable I have heard horror stories of marketer's losing their lists because they scrimped on the $19 a month.
Hope that helps
It depends also on what kind of marketing you are doing, a self hosted setup is also a good option and one that more and more marketers are adapting to If you can get some one to install interspir, sendy or mailwiz with Amazon SES , MailGUN or SendGrid and SMTP providers, you can get as good results as ESPs like aweber and get response Plus you never have to worry about getting shut down for any reasons. Think about it..