Commissioner Tadpole
Spazmatism
I prefer Crimson because the red gore theme is a bit more creative than the purple diseased theme in my opinion. The Crimson also feels more of a threat to my world and something that I cannot allow to spread at any cost as it turns the land itself to rotten flesh, while the Corruption feels more of a leech that I'd love to tear off of my world as soon as I get the chance. That said, the Crimson's threat-level works too well at times, and I'm often outright afraid of the Crimson due to the Face Monsters and Herplings - as well as the human skull background that I fortunately have never personally seen yet. So whenever I create secondary worlds, they're almost always Corruption.
However, the Corruption also has some really nifty content like the Band of Starpower and the Worm Scarf, which I cannot seem to be able to live without. I often never use the Crimson-exclusive items like the Fetid Bagnakhs, Fleshy Knuckles, Life Drain and Vampire Knives, while Corruption items are used with more frequency by me. (The sole exception is the Golden Shower, that thing carried me through almost the entirety of Hardmode, if it weren't for the Lunatic Cultist's invulnerability to Ichor and the fast pace of the Moon Lord's fight - Crimson armour was also lovely and carried me until I decided to upgrade to Molten). So I'd say that in terms of ambience and atmosphere, I prefer Crimson due to its scary ambience and threat, while in terms of loot and rewards, I prefer Corruption.
However, the Corruption also has some really nifty content like the Band of Starpower and the Worm Scarf, which I cannot seem to be able to live without. I often never use the Crimson-exclusive items like the Fetid Bagnakhs, Fleshy Knuckles, Life Drain and Vampire Knives, while Corruption items are used with more frequency by me. (The sole exception is the Golden Shower, that thing carried me through almost the entirety of Hardmode, if it weren't for the Lunatic Cultist's invulnerability to Ichor and the fast pace of the Moon Lord's fight - Crimson armour was also lovely and carried me until I decided to upgrade to Molten). So I'd say that in terms of ambience and atmosphere, I prefer Crimson due to its scary ambience and threat, while in terms of loot and rewards, I prefer Corruption.