Divine Crate

Every other biome crate has a guaranteed item bolted onto its table. This one does not, and the gap works in your favor: a roll that produces nothing from the main groups is simply thrown out and rolled again, so the entries you care about land around twice as often as the printed odds suggest. The practical result is that a lake in the Hallow hands out more hardmode ore and bars than fishing anywhere else in the world.

Souls of Light and Crystal Shards both show up regularly, and both are otherwise chores. Shards mean crawling the underground Hallow scraping walls, souls mean grinding kills down there for a stretch. If you were going to fish for metal anyway, half of your early hardmode crafting materials arrive in the same crates without a second trip.

You need hardmode and you need Hallow water. A natural lake is fine, and so is a pool you convert yourself, since the game only checks the biome around you when the line goes in. If your world dropped the Hallow somewhere awkward, moving the water rather than moving yourself is usually the faster fix.

Nothing here is exclusive. No weapon, no accessory, no mount is locked behind it, so this is a supply line rather than a target, and once you have enough bars there is no reason to keep casting. Its pre-hardmode counterpart is the Hallowed Crate, and you can push a Divine Crate through Shimmer if you want that version instead. The Defiled Crate and Hematic Crate cover the two evil biomes, but neither gets the reroll, so neither comes close on ore throughput.