Recently lost access to Kucoin due to losing GAuth codes. Contacted Kucoin and gave details requested. I received a reply within a week with an apology for taking so long to reply!!! I was informed access without 2FA would be restored in 3 to 4 days. As it was weekend I thought the middle of the week but restored on Monday,today. Any other exchanges with such quick support?
That's not quick support at all with over a week's turnaround.
What I would call quick support would be anyone answering to my support tickets within 24 hours of me posting them. Also they should have a strong presence on social media platforms and answer questions there when needed.
So while kucoin may be average or decent in terms of speed, and they certainly have at least attended to your issue, they are not fast by any means.
The fastest right now could be binance, I haven't heard any major complaints about their support speeds.