Three of the strongest 1K image models on the market — Google's Nano Banana Pro, Black Forest Labs' Flux 2 Pro, and ByteDance's Seedream V4 — and they all have meaningfully different personalities. After running 60 prompts through each, here's when we'd reach for which, and where the costs actually land on Kunavo.
The contenders
- Nano Banana Pro — Google's flagship image generator. Best in class on text rendering (signs, labels, UI mockups). Strong photo realism but slightly soft on fine detail.
- Flux 2 Pro — Black Forest Labs' latest. The sharpest photorealism in the set, especially skin and fabric. Less reliable on text. Slightly conservative on stylization.
- Seedream V4 — ByteDance's aesthetic-leaning model. Excellent at illustration, editorial, and stylized work. Tends to romanticize prompts — adds warmth and depth the prompt didn't ask for.
All three on Kunavo at 30% under the upstream rate. Identical OpenAI API surface — only the model slug changes:
# Same client. Same code shape. Different model.
# All three return a temporary URL you can download.
from openai import OpenAI
client = OpenAI(
api_key="sk-kunavo-...",
base_url="https://api.kunavo.com/v1",
)
prompts = [
"a glass-walled tea house at the edge of a misty forest, golden hour, "
"cinematic, 50mm lens, shallow depth of field",
"a vintage Italian espresso machine on a marble counter, soft window "
"light, food magazine photography",
"a stylized cityscape map of Tokyo, isometric, pastel colors, "
"labeled districts in elegant serif",
]
for prompt in prompts:
for model in ["nano-banana-pro", "flux-2-pro", "seedream-v4"]:
resp = client.images.generate(
model=model,
prompt=prompt,
size="1024x1024",
)
print(model, resp.data[0].url)The categories
Photorealism (product, food, portrait)
Winner: Flux 2 Pro. Especially close-up product photography — the espresso-machine prompt produced a Flux 2 image that could have been pulled from a Williams Sonoma catalog. Nano Banana Pro was solid but soft on the chrome reflections. Seedream warmed the colors and made it look more like a Vogue editorial than a product shot — sometimes that's what you want, sometimes it isn't.
- Sharp photo realism: Flux 2 Pro
- Editorial / lifestyle photo: Seedream V4
- Cinematic with depth: Nano Banana Pro (the bokeh is genuinely cinematic)
Text and labels (UI mockups, posters, signs)
Winner: Nano Banana Pro, no contest. Google's model is on a different level here. Multi-line text, varied weights, and brand-style consistency all work first-shot. Flux 2 Pro produces plausible-looking gibberish; Seedream tries and usually mangles the spelling on anything past 3 words.
If your use case includes any rendered text — Twitter card mockups, product packaging, infographic posters, app store screenshots — start with Nano Banana Pro and only reach for the others if the aesthetic doesn't fit.
Illustration & stylized work
Winner: Seedream V4. The isometric Tokyo map prompt produced a Seedream image with the kind of considered color palette and compositional balance you'd see in a New Yorker spot illustration. Flux 2 went photorealistic-with-stylization, which looked like a misunderstanding. Nano Banana Pro hit a competent middle ground.
Seedream rewards descriptive prompts about the aesthetic. Give it a reference style ("in the style of mid-century Japanese woodblock prints, muted indigo and ochre") and it leans in. Flux 2 is a literalist; Nano Banana Pro is in between.
Long, complex prompts (multi-element scenes)
Mixed. All three handle three-element scenes well. Four or more elements with specific spatial relationships ("cat on the left, lamp on the right, window in the back, book on the floor") and they all degrade — usually one element gets dropped or duplicated.
Nano Banana Pro had the best spatial accuracy in our 60-prompt set; Flux 2 Pro the best lighting consistency across elements; Seedream V4 the prettiest single-element rendering even when the composition failed.
Cost (per 1K image, on Kunavo)
All three are billed per-image, not per-token. The per-call sticker on /pricing:
- Nano Banana Pro: ~$0.07 per 1K, ~$0.14 per 2K (the most expensive of the three, but the text quality is worth it for the right use case)
- Flux 2 Pro: ~$0.05 per 1K, ~$0.07 per 2K (great value for photorealism)
- Seedream V4: ~$0.03 per 1K (cheapest of the three; the <-30% discount makes this very competitive)
Failed calls aren't billed — if you misspell the model slug or the upstream rejects your prompt, your wallet is untouched. See /docs/billing for the full rules.
Which one should you start with?
- Building a UI mockup tool, marketing asset generator, or anything with text in the image? Nano Banana Pro. Don't even start with the others.
- Building a product catalog generator, real estate visualizer, or food/portrait photography pipeline? Flux 2 Pro. The realism per dollar is excellent.
- Building an illustration tool, editorial cover generator, stylized icon library? Seedream V4. The aesthetic is worth experimenting with even if the prompt-following is slightly looser.
- Building a general-purpose tool that needs to handle all of the above? Default to Nano Banana Pro, let users override to Flux 2 for photo-only flows and Seedream for illustration flows. The UX of one default with two escape hatches beats forcing every user to pick.
Image editing — separate question
All three have -edit variants for image-to-image work: Nano Banana Edit, Flux 2 Pro Edit, Seedream V4 Edit. The relative ordering is similar: Nano Banana Edit handles text replacement best, Flux 2 Edit preserves photo realism best, Seedream V4 Edit re-styles best. Same /v1/images/edits endpoint, just pass image_url.
Try them yourself
The whole catalog is at /models, filterable by category. The fastest way to compare is to grab the $2 free credit, run the snippet above with your own 5 prompts, and let your eyes pick. Image taste is personal — our shootout reflects what we shipped after running 60 prompts, but your aesthetic might prefer Seedream where we picked Flux, or vice versa. The shootout that matters is the one you run on your prompts.