DeepSeek V4 vs Claude Opus 4.7 vs GPT-5.5: I Tested All Three on Real Business Tasks
Three frontier AI models all launched within a week of each other. I decided to spend two days putting them through the kind of tasks small business owners actually run.
By Sam Frost
Published Apr 27, 2026 · 5 min read

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Last week saw three of the biggest AI model launches of 2026. Anthropic shipped Claude Opus 4.7. OpenAI followed with GPT-5.5. Then DeepSeek dropped V2, an open-source model from China that costs roughly a tenth of what its American rivals charge.
If you run a business that uses AI for anything important: writing, coding, customer support, research, document analysis, you’ve got three new options to consider. Right now, most of the comparisons out there are benchmarks. Numbers that might look impressive on paper but mean nothing when it comes to helping you execute.
So I decided to run my own tests. Seven tasks pulled from the kind of work I do every day across my business. The same prompts for each.
Before I get into the business tests though, I wanted to start with something even simpler.
Test zero: a setup test, not a serious one
Before running the actual business tests, I wanted a quick gut-check. This is more of a warm up to set the scene before things get more rigorous. The prompt:
I want to wash my car. The car wash is 50 meters away. Should I walk or drive?
This is a question with one right answers: you drive. The car needs a wash. The results are an interesting illustration of each model’s personality. DeepSeek V4 Pro got it right and seemed to show a lighter side with some humor. GPT-5.5 also got it right and got there the fastest. Claude Opus 4.7 got it wrong and confidently.
One prompt, not a serious test. But important because it tracks with something I’ve noticed using Claude Opus 4.7: it’s more willing to push back and disagree with the user than previous versions, even though it can be wrong. DeepSeek leaned into personality, something it lacked in V3.2. GPT-5.5 was efficient to the point of bluntness, it has been accused of rambling on in previous versions.
With that out of the way, here’s the actual tests.
Test 1: handling a tricky customer support email
The first real test is something every business owner has to deal with: a customer wants something they’re not entitled to, and your job is to say no without causing even more problems. Here’s the prompt:
A customer has emailed us asking for a full refund on a $299 software subscription. They've used it for 3 weeks. Our refund policy is 14 days. They're claiming the software is 'much harder to use than expected' but our records show they've completed 4 of the 7 onboarding steps and used the product 12 times. Write a reply that declines the refund but offers a free 30-minute onboarding call instead. Tone should be empathetic but firm. Don't mention the policy by name like a robot, just explain naturally.
This is both a test of judgment and writing. The model has to hold a position the customer won’t like, do it without sounding like a robot, and pivot to something that will solve the customer’s complaint.
All three models passed the basic test, but the differences were shaper than I expected. DeepSeek V4-Pro produced the most send-ready email of the three, with a tight structure and nice reframe of the customer’s frustration into something positive. GPT-5.5, despite hitting every required beat, felt like it was written by AI, without any character. I can’t help but wonder if that would further frustrate the customer. Claude Opus 4.7 wrote the longest and perhaps most human of the three and provided its reasoning which is useful if you’re using AI as a collaborator and complete noise if you just wanted the email.
For pure send output: DeepSeek V4-Pro wins. The email is ready to go without editing. For collaboration: Claude Opus 4.7 wins. The email itself is strong and the notes are genuinely useful.
One issue: every model used em-dashes liberally. This matters if you care about your writing not reading like AI wrote it. Most people are fully aware that em-dashes are a sign of AI output. All three would need a quick edit before ending.
Test 2: drafting a contractor agreement clause
Most small business owners draft their own contracts because hiring a lawyer for every $5,000 freelance project doesn’t make financial sense. This test was designed to see how the models handle a real agreement drafting task with competing interests on both sides. Here’s the prompt:
Write me a 'scope of work and revisions' clause for a freelance contract. Context: I'm a marketing agency hiring a freelance designer for a $5,000 project: logo, brand guidelines, and 5 social media templates. I want to limit revisions to 3 rounds total to prevent scope creep, but I want it worded fairly so the freelancer doesn't feel pinned. Plain English, no legalese. Make it the kind of clause both sides would sign without arguing.
All three produced something usable, but the gap between them was the largest so far. DeepSeek V4-Pro wrote what feels like a real freelance contract written by someone who has been on both sides previously. It has clear definitions for each revision round, explicitly calls out what doesn’t count as a revision, and then includes a “quick note on the spirit” closing paragraph that humanizes the legal language. GPT-5.5 wrote something that feels generic and perhaps a little too tight. All the elements are there, but it reads like a template file from a random PDF you found online. Claude Opus 4.7 powered in with the most detailed agreement covering edge cases the other two didn’t (silent client approval, what counts as new scope vs revision, revision tracking). The level of detail is impressive but another fine example of Opus overthinking. Claude wrote a clause for a $50,000 engagement; DeepSeek wrote one for the $5,000 brief.
The clear winner this time: DeepSeek V4-Pro. The clause is the right length, right tone and gets the job done.
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