I think that for this reason, we should use services that do not require registration. This may be Changelly or Changenow, but the last exchanger seems to me the most optimal since they offer a fixed rate. But I think that everyone should choose a service that suits him.
Changelly/Changenow is more to become a scam than Bittrex. The company is even tagged with a red/negative trust here in bitcointalk. If you don't trust Bittrex anymore than yoou can choose the other big exchange like Binance.