One of the products my company offers is personalizing images with merge variables. Recently we built an option that let's customers upload Photoshop(PSD) files, we recognize variables on different layers of the PSD, then give them an Image URL to use in their email templates.

Example with one variable:

My question is what other tools do you prefer for image design? What "integration" should we focus on next to make sure the product appeals to the people in this community? Sketch? ?? Please let me know, even is someone else already mentions it, we are doing a poll of sorts.