Can I challenge you on what you think is a "amazing display ad?" Are you looking for brand or image appeal, or more concerned about return on ad spend (generating traffic, vs. leaving an impression). From a quantitative perspective (money spent > amount of traffic > amount of conversions/objectives achieved), ONE (cut into many sizes) design is rarely enough.
A few things which we are all aware of:
- Display ads works with strong brands because, well, that's what a brand is. It engenders trust and familiarity. So, if you're relatively unknown brand, then you fall into the unknown random banners that pop up. Maybe the value or benefit is a stronger message then what Nike can get away with just a swoosh.
- Banner Blindness is real, and the same banner/design builds fatigue over time - you just stop looking at it if it's the same one. So frequent changes and messaging needs to happen.
- If you are looking for conversion/traffic, then there's not one-design that works. It's a constant iteration and testing of targetting, message, design. You may look into tools that help you modify them faster. Google has a decent tool: http://www.google.com/ads/displaynetwork/build-your-ads/display-ad-builder.html - but we use scripts/programs to generate hundreds if not thousands of banners to test. And I tell you, I'm constantly surprised by what works. (Changing one word, or one color, or position of buttons, affects the CTR).
Hope that helps, didn't mean to put you on the spot.