I'd say aweber is the best. I also use mlmpowermarketing for converting free leads into premium leads.
use aweber, article market send traffic to a landing page with an email capture give something away for free to entice them to sign in
I've used both aweber and getresponse. I'm with getresponse right now but you won't go wrong with either of them. The ~$20 per month is a good investment in your business.
thanks all! I've decided to go with emailbrain, since it's cheaper and I don't need to send many emails yet.