I had a wee play with my camera yesterday to see what difference the AWB and Custom settings on my Canon 300D actually makes.
I make no excuse for the quality of these photos, they were treated exactly the same (Manual exposure, 1/200 @ f8 and used a Photoshop action) except the first one was set to the AWB setting and the second used a Custom white balance derived from a Lostolite grey balance card.
In the end it boils down to personal preference and I tend to prefer removing the colour cast.
Auto White Balance Setting

Custom white balance

Just for the record here is the reference grey card photo
I make no excuse for the quality of these photos, they were treated exactly the same (Manual exposure, 1/200 @ f8 and used a Photoshop action) except the first one was set to the AWB setting and the second used a Custom white balance derived from a Lostolite grey balance card.
In the end it boils down to personal preference and I tend to prefer removing the colour cast.
Auto White Balance Setting

Custom white balance

Just for the record here is the reference grey card photo

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