There's stuff out there....I actually think you can get a 1908 NM MS-66 for just above $3,000. Certainly, common Saints in MS-65 are well under $3,000 (1924, 1927, and 1928).
I believe here is the ultimate MS-66+, CACed "thrift" coin, requested in post(s), complete with what I would consider gross "bag-marks/bag-rub", device/field-marks/blackened-surfaces, lack-luster, etc., for only, $5800: https://www.nfccoins.com/products/18304 I'd posted a believed labeled PQ prime example of an initially requested coin, sans afore-mentioned deficiencies, with beautiful "cart-wheel" luster, available for less than $4000. I just purchased the coin from a "market-leader", to ascertain images were as believed, correct! They were!! JMHO
Is it just me or does the coin look "dirty ?" And yet....it got a "+" designation AND a CAC from JA. And he's tough on gold and Saints, let alone the WF Hoard. The reverse is better than the obverse but not enough to compensate for all the dings, dirt, etc. Same 66 grade ? I believe it.
Yes, that is called "bag rub", all the distance from the flattened fore-head/nose, breasts, arm, leg, standing-rock, rays, some field. JMHO
My 1915-S has black specks which do NOT appear to be part of the coin, like little black pepper flakes. But I got a good price on it and it's basically a bullion coin with good luster:
I'd personally select your believed under-graded 1915-S MS63? before the 1908 NM MS66+ CACed. I believe the wholesale value of your coin to be ~$3000. The other coin was probably acquired for ~$4000. I believe yours has the greatest future value potential, even with the relatively diminished "bag rub"! Your coin has beautiful "presentation" with "cart-wheel" luster, normally rarely seen in MS63 grade. JMHO
Thanks IM...your expertise is always appreciated. I was lucky as I think I got it the last day of FUN 2020 or late-Saturday...got a good price, I think a small premium to the spot price.