Finally I tested b1exch.to and everything were done smoothly for my first experience with this exchange. It's impressive.
No registration required.
No email.
No KYC.
Nothing, just go to the exchange, and do your trade with BTC to different altcoins and vice versa.
It is possible to use with Tor, that's great.
I choose to swap BTC to XMR, and the fee is 4% ($5.91 in my case) that is quite high in my opinion. I did not test with other altcoins yet, but in some posts above and hopefully they will give cheaper fees.
Most of steps are detected automatic like my deposit, to processing of the exchange.
Rate seems to be update about 8 minutes. I did not notice it when I start the trade but a few time later, I looked and see the countdown timer was already less than 8 minutes.
With my trade, the processing time for BTC to XMR is slow. At starting of the output processing, the timer is 16 minutes.
It is a quite long waiting time with XMR but I found this with b1exch's FAQ.
https://b1exch.to/FaqWhy is my Monero order taking so long?
We use a single wallet for all Monero transactions. Due to protocol limitations requiring 10 confirmations before UTXOs are spendable, multiple Monero orders may cause delays. We use multiple pools to speed this up, but significant amounts may take time.
After all, it was done after about 25 minutes.