If you want to take your marketing campaigns to the next level, you've got to test them. How do you do that? With A/B testing. It's sometimes called split testing. What is A/B testing? It's basically comparing two versions of a web page, email or banner to see which one performs better.
You can compare these by showing the two variants, calling them A and B, to similar visitors simultaneously. See which one gives the best conversion rate and then use that one moving forward! It's simple, but also necessary.