Simple question, difficult answer.
Many mixers are active on Bitcointalk but how long will each one last?
Seems to be just a matter of time until we'll have our next mixer shutdown.
Pick your one, which is next!
Did you mean we should pick only from those ones active here? Well, I will not do that because that would amount to wishing them bad luck.
I can only advise them to work with their conscience unless they do not know about the main things their services are being used for. Some are not familiar with what they are doing ignorantly but some are indeed familiar with it but don't just care. They might want to do a very good business that is void of the blame that could cost them their company for them to stay longer.
Many mixers have been banned in the past, and of course, this last one will not be the end. And to crown it all, no one knows the next one, maybe the law enforcers will be able to answer that based on their investigations.