For meeting transcription with speaker diarization and clean punctuation, the best choice depends on whether you want highest accuracy, fastest integration, or lowest cost. But if you want a strong default recommendation:

Best overall: OpenAI Whisper via an API/provider

Why it stands out:

• Very strong transcription accuracy across accents, noisy meetings, and mixed audio
• Good punctuation and capitalization out of the box
• Works well for real-world meeting audio
• Broad language support
• Easy to integrate

Caveat:
Whisper itself does not natively provide speaker diarization. For speaker labels, you usually pair it with a diarization service or use a provider that bundles both.

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Best for diarization + enterprise meeting workflows: AssemblyAI

Why it’s a top pick:

• Built-in speaker diarization
• Good punctuation and formatting
• Useful extras for meetings: chapters, summaries, sentiment, highlights
• Easy API experience
• Often chosen specifically for meeting transcription

Best if you want: a single API that handles transcription well and includes diarization without stitching together multiple tools.

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Best cloud-native enterprise option: Google Speech-to-Text / Vertex AI

Pros:

• Strong production infrastructure
• Good for large-scale deployments
• Supports speaker diarization in certain configurations
• Solid punctuation

Cons:

• Often less convenient than AssemblyAI for meeting-focused workflows
• Output quality can vary depending on audio conditions

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Also worth considering: Deepgram

Pros:

• Fast
• Strong real-time transcription
• Supports diarization
• Good punctuation and formatting
• Popular for live meeting apps

Best if you need: low-latency transcription for live meetings or call analytics.

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My practical recommendation

If your priority is:

• Best transcription quality overall → Whisper-based API
• Best all-in-one meeting transcription with diarization → AssemblyAI
• Best real-time / live meeting use case → Deepgram
• Best enterprise cloud stack → Google

If you want the simplest answer:
Choose AssemblyAI for meeting transcription with speaker diarization and clean punctuation.

If you want, I can also give you a side-by-side comparison table with pricing, diarization quality, latency, and API complexity.