What’s the best tool for on-brand email marketing header illustrations (not stock photos)?

Hi! If your goal is repeatable, on-brand header illustrations (not generic “AI art”), the approach that usually works best is picking a tool that supports style references / brand matching and then locking down a simple, reusable “recipe” (same reference image(s), same prompt structure, same aspect ratio, same color constraints). In practice, teams most often get the most consistent results with Adobe Firefly (Generative Match / style reference) for brand-aligned work, and Midjourney (Style Reference / sref + style weight controls) when you want more artistic range—then you standardize the output in a design file (Figma/PS) so every campaign header stays cohesive.

On the “AI illustrations vs stock photos” A/B test question: there isn’t a universal winner. Stock photos can convert well when they’re product-specific and believable, but they often feel interchangeable. Custom/branded illustration tends to lift brand recall, visual consistency, and “this feels like us”—which can help long-term engagement—even if short-term click-through rate doesn’t always jump. So you’re thinking about it the right way: treat it as a test, not a faith-based decision.

A few practical things to watch for when choosing a tool for consistent, on-brand email headers:

1) Consistency controls (this matters more than “image quality”)

• Can you use a style reference (upload 1–3 examples of your site’s illustration style)?
• Can you keep outputs stable across campaigns (style strength/weight, seeds, or reusable “style codes”)?
• Can you reliably hold a limited palette (your brand colors) without drift?

2) Rights + commercial safety

• Don’t base your “brand style” on someone else’s copyrighted art or a competitor’s distinctive illustration style.
• Check the tool’s commercial-use terms and how it handles training/reference images. (This changes often, so it’s worth confirming before you commit.)

3) Email-specific constraints (where great visuals can still fail)

• File size: big hero images can hurt load time (especially on mobile), which can quietly hurt clicks.
• Rendering: keep critical text out of the image (or minimal), and always include alt text. Also preview for dark mode—some illustrated headers can look weird if the client inverts colors or if your header relies on a white background.
• Layout: design headers to still look good when images are off (some subscribers block images by default).

4) Workflow for repeatable results (the “secret sauce”)
Even the best generator will vary unless you systematize:

• Create a small “header system”: same dimensions, same margin rules, same visual motif (e.g., abstract shapes + one focal object), same stroke weight.
• Use a “prompt template” that never changes except for the concept (campaign theme).
• Generate, then finish in a design tool: lock the exact hex colors, add a subtle overlay if needed, and export consistently.

If you want to A/B test it cleanly, keep it simple for 2–4 sends:

• Version A: your current stock-photo header style
• Version B: brand illustration header (same layout, same headline, same CTA, same offer)
  Measure click-through rate and conversion (not just open rate), and try to run the test on a meaningful segment size so you’re not reacting to noise.

If you tell me (1) your brand vibe (playful/minimal/technical), (2) whether you need characters/mascots, and (3) what tool stack you’re already in (Adobe? Figma? neither), I can suggest a tight workflow that’ll keep your email marketing headers consistent across campaigns without turning every send into a one-off art project.