Monster Rearing - Best Collecting Item Creatures

What creatures yield the best "collect" items?

I am down to my last 3 cheers. After I collect all the cheers I wanted to raise the creatures that yield best collect items.

I never raised a creature for very long before having to release them after the cheer, so my knowledge of the collection items is limited. The red dragon seemed to be the most consisted with gem stones, but is there a better creature to use?

Adamantoise. They give you shells that you can NPC for ~12k or 15k... something to that tune.

Dragons can give you gems, but the most that tends to turn around is ~5k.

Though dragon gems are more common than adamantoise shells, so it's quite possible that 4x wyrms give you a better average than 4x adamantoise. But I do suspect that adamantoise would still wind up the winner, since most gems you get will be a only few hundred to 1k gil max.

Thanks! Looks like my garden is gonna be one big earthquake zone.