Aweber is probably the most professional one and with the most features, but it's very expensive for casual / newbie users like you seem to be
In the past I have also tried GlobalNPN (for a few months only, and that was 10 years ago or so, so I'm not sure how / if they have changed drastically, but at that time I've been pleased with them).
TrafficWave have also been good, functionality-wise, but I've had a minor issue with them 10 years ago (I don't remember what the issue has been, though) and I got pissed and cancelled my account with them. But, you might not run into that issue, so they might be appealing to you.
BirdSend is what I'm currently using and they're relatively new on the market so they don't offer a lot of customization yet, but they're working on it and this year alone several improvements have been done.
MadMimi... I have only used for a few months 5-6 years ago and I've enjoyed their pricing model, and the goofy design of their site (yeah, I'm one of those few people who don't give a crap about design if the functions I'm paying for work flawlessly). I've been happy with them at that time.
I've never tried the others, but I've seen them being mentioned often which is why I've mentioned them. Whether they are good or bad I can't tell, obviously, but... they're an option, just in case....
If I were to recommend you one of these it would probably be MadMimi. If my memory serves me well I was paying $10-12 per month for 500 subscribers, which is very good for a newbie. If those subscribers are targeted and nurtured they could potentially pay you $1000s a month, which is enough for you to upgrade to a better plan.
I don't know if / how MadMimi (or any of these services actually) have changed over the years cause I've stopped using them but - like I said - I would recommend MadMimi (IF they haven't screwed things in the meantime)
