What I believe should be removed from the existing table and why:
Cenozoic/Mesozoic/Paleozoic Stones: These are such common drops in game that putting them on the o clay system is both pointless and frustrating. Nothing makes me rage more than reach R5 O clay and getting a stack of worthless crap I won't ever use as a reward.
Sapheal's X of the Earth/Sky: Also very common, gained from boss drops and whatnot and not really worth putting in o clay.
Fragments: Another common drop placed on the o clay table. I wouldn't mind say... full stacks of platinums or half stacks of mystery/blood fragments, but beyond that it's not worth it.
Dimension Crystals: These can be gained through PvP. Removing them from O clay would have a (very slight) positive effect on PvP activity.
Ultimate Mousou/Judgement Resonance Stone (Variant): Just no. No one uses these at all, I'd say replace it with something like an ancient res stone formula (the 66+ ones) or a relatively stong kuso stone for crit rate or damage, rotating daily between magic and physical
Stone of Special Insight: I don't believe this should be completely removed, but I do think it should be put on one of the lower tiers, so that people who have maxed their masters aren't stuck with a non-tradable item they will never use, and can just go to the next round
What I believe should be added to the table and why:
Stacks of powers for alter fame: Grinding powers is mind numbing, even when dungeon grinding, I'd spend SOOOOO much gold on O clay if I could get stacks of powers from it, especially the higher end ones like frost, or convertible ones.
Ancient Resonance stone formula/high level kuso crit damage/rate stone: to replace the judgement/mousou variant stones
Extreme HP/MP stones: Only being able to get them from tiered spenders, quite frankly, sucks hard for most players.
10 x enchantments of various levels: Simply because they're pretty scarce and always in demand, make them NT.
Will add more at some point