They're both great colors, but with the etain you probably won't see any color transfer on the bag if you're wearing denim. Remember, because it's a crossbody, it's going to constantly rub up against your clothes.
Both are classic. Is etain in Epsom and etoupe in Clemence? Maybe choose based on which leather you prefer otherwise I would go for either one as both of them are pretty classic neutral color and you can't go wrong with these. If I have to really pick one, I am leaning more towards etoupe just because I like the color more and also for the contrast stitching.