I say, and with God's success: These are expressions of preference, and their use depends on the speaker. There is no precedence of one over the other unless they come from one person, in which case 'Al-Ashah' is preferred over 'Al-Sahih'. A fatwa cannot be issued based on the expressions of preference until it is confirmed that it is supported in the school of thought and that it is the strongest. And God knows best.