While any of them can increase the power of your deck, youll see way more gains by spreading that $20 or so across multiple cards, at least for initial upgrades
Scanning damaged cards allow them to live on in digital form so that you can still eke out some value from your purchases, plus you can scan foreign language cards to then have them show up in your digital library in the language you have set in the app
Celestial Archon I can see Celestial Archon in Voltron-like strategies where you want a flexible enchantment that can sometimes be used as a creature for your auras to target
Particularly for popular Pokmon, limited promos, vintage cards, and modern high-rarity cards, the buying and selling price can fluctuate significantly based on the evaluation, even if they look similar
Cryptolith Rite gives all your critters the same power as Birds of Paradise, tapping to produce mana of any color you want