Round 1 – https://blog.ciaops.com/2026/07/30/comparing-llms-in-copilot-services-round-1-chat/
Winner – Opus
Round 2 – https://blog.ciaops.com/2026/08/08/comparing-llms-in-copilot-services-round-2-researcher/
Winner – Critique
Round 3 – https://blog.ciaops.com/2026/08/11/comparing-llms-in-copilot-services-round-3-cowork-claude/
Winner – Opus 5
Round 4 – https://blog.ciaops.com/2026/08/12/comparing-llms-in-copilot-services-round-4-cowork-gpt/
Winner – GPT 5.6 Terra
Round 5 – https://blog.ciaops.com/2026/08/14/comparing-llms-in-copilot-services-round-5-cowork/
Winner – Opus 5
Round 6 – https://blog.ciaops.com/2026/08/16/comparing-llms-in-copilot-services-round-6/
Winner – Opus 5
I’ve been pitting different LLMs inside M365 Copilot against each other ina world cup style elimination to see which comes out on top. The process involves taking a standard prompt and running it against all options. This prompt creates a multi page document requiring deep research and is quite involved. The results are then compared against each other using SharePoint Copilot and Gemini. Conclusions are then drawn.
For the final, we have Opus 5 (Cowork) and Opus (Chat). The results are:
https://github.com/directorcia/general/blob/master/Copilot/Comparisons/20260816-Copilot-Grok-eval.md
1. Opus 5 (Cowork)
2. Opus (Chat)
Therefore, the initial over all Copilot LLM winner is a clear win for:
Opus 5 (Cowork)
The trade off is that the cost for this US$22, while the runner up’s price was included in the cost of a Microsoft 365 Copilot license.
These test have revealed a few things, in my opinion:
A. Claude Opus is the superior model
B. Opus in chat is almost as good as Opus Cowork but much cheaper
C. For most work Opus in chat is probably you best option
The challenge with these report, as with any LLM’s is they are not definitive. Another round could reveal completely different results as could the method of evaluation, however as a best effort I think it does have validity and provide some general findings that do help understand the model choices in Copilot.
For comparison, I have create a document parameters page here:
https://github.com/directorcia/general/blob/master/Copilot/Comparisons/20260816-File-paramters.md
so you can now compare all the various output document sizes, pages, etc to each other. I have also made available a copy of each model output document, without any changes to it, so you can look at each for yourself. You will find them all at:
https://github.com/directorcia/general/tree/master/Copilot/Comparisons/20260816
The idea is to wait until we see new models appear in Copilot and use the same methodology against these also when they appear. That will hopefully provide some sort of bench mark when it comes top model strength.
I hope this series of tests has been interesting and helpful to you and I’d love to hear your thoughts on the results.