Gpt4o mini transcribe is better and actually realtime. Whisper is trained to encode the entire audio (or at least 30s chunks) and then decode it.
The linked article claims the average word error rate for Voxtral mini v2 is lower than GPT-4o mini transcribe
So "gpt4o mini transcribe" is not just whisper v3 under the hood? Btw it's $0.006 / minute
For Whisper API online (with v3 large) I've found "$0.00125 per compute second" which is the cheapest absolute I've ever found.