Ease of use, responsiveness, interface and price. I switched to Benchmark from Constant Contact two years ago and I love it! It is easy to use and intuitive. The price is great for my SMB clients. I also love the reporting.
I love the service but when a list is regected, it is not immediately clear why. Also, I would love to be able to see a separate list with regected emails. One of my clients has a really large list and that would make scrubbing the lists easier.
Definitely a great solution for SMBs. Tiered pricing model makes it easy to market to lists of all sizes.
Simple to use and cost-effective solution for email marketing. I didn't realize how easy and intuitive it would be.