. I've used Silverpop for about 5+ years and used ExactTarget for a couple of years now. They both have pros and cons. From my perspective, which is mostly front end development, I think they both do some things really great, but neither do the same things really great and they both have their trouble spots. I don't do anything with reports, APIs, etc. and not much with setting up automation, although I have done some. So others can speak on how well both platforms perform for those functions, but from and ease of setting up emails, lists, test, landing pages, etc. I have used both quite extensively. The thing that is usually the biggest learning curve is now they handle dynamic content. Silverpop has a UI for creating conditional blocks of content. This makes it easy once you get your head around how it works, but isn't real intuitive in my opinion. But it doesn't make it much easier for a non programmer to create dynamic content, but that doesn't mean it's easy for a non-technical person. It can be, but by it's nature, it's a logic based syste I've seen many others (client service) people have a hard time understanding how it works. ExactTarget, on the other hand, has a proprietary scripting language (AmpScript) that makes for a whole new world of possibilities. The language makes sense to programmers, but I've found it pretty painful to find script examples of some pretty basic things. But, once I found out how to do a few things, it made the next challenge that much easier, so I'm getting the hand of it. One big stumbling block with Silverpop is the ability to nest dynamic content within dynamic content. We have successfully made it work, but they don't officially support it, and the UI does not make it easy to do it. I have not tried it in AmpScript, but it seems like it would work. And with AmpScript, I can see the code and see what's actually going on. With SP the UI is writing code that we never see, so you're never quite sure what's going on behind the scenes. Those are the only two I've used. I did a little freelance work in Constant Contact, but can't really compare it with enterprise ESPs like SP and ET. I also worked in Neolane very briefly, but can't really commit much on that. It was not browser based, so I didn't like that, but I shouldn't judge it by that. It might be really great. Both Silverpop and ExactTarget have pretty good tech support, but we've had some very specific issues and it was hard to nail down the right person to get the right answers. We're still in the middle of a couple of those issues, so stay tuned.