I've used multiple marketing email clients but Benchmark seems to have more control over the look and feel of an email than the competition. That can be a good thing if you know what you're doing.
The learning curve for Benchmark can be steep. I've been using Benchmark for a while so I know my way around pretty well, but, it took a while to get up to speed.
If you're confident in your email design skills, then Benchmark will be easy for you to learn. You'll have a lot of control over the look of your emails and have the ability to do just about whatever you want to do.
Benchmarks customer service is stellar. . .the best. Any time I have had a question, day or night, they are there to help. I haven't come across a problem yet that they weren't able to solve. They've helped us increase our open rate as well with their analytic tools.