which cowboy junkies cd?

The Trinity Sessions.

The first three albums would be a good start (Whites Off Earth, The Trinity Sessions, The Caution Horses).

Listening to "Whites Off Earth" may cause you to see their later work in a different manner/light.

Not familiar with 2003 onward releases, and only dislike "Open" (2001?), which never grew on me.

There is an odd/foreign noise on the first (vocal?) track of "The Trinity Sessions" which is normal/as it should be.

My favorite is "Lay it Down". I don't see too many folks citing a similar preference, but IMO that's the one with the best songs all the way through. Trinity Sessions surely isn't a bad place to start and it has that unique "airiness" given the way it was recorded. "One Soul Now" is also good.

Truth is I don't think there is a bad Cowboy Junkies CD.

The newest one is excellent too; Early 21st Century Blues. That and the Trinity Sessions are their two best releases in my opinion. Trinity Sessions is an audiophile favorite for the incredible sound quality, 21st Century isn't in the same league soundwise but the music is every bit as good.