I like both of them. Both have great themes - Crimson's aesthetically tighter, but the Corruption's music is more enjoyable to me. Gameplay, too. The Crimson is definitely better to have in hardmode, because ichor is god, Fetid Baghnakhs are double god, and Vampire Knives are please take all of my money. Corruption's fairly lame in hardmode unless you're playing expert, wherein the Worm Scarf makes the lack of Vampire Knives... if not worth it, at least on equal footing.
The thing I love about Corruption that Crimson can't match, though? Ancient Shadow Armor. I can sit in a box and prod at Eaters with a wooden yoyo, and when that first piece drops... I feel like a king. Getting Shadow Armor before I even get iron, it's a magnificent feeling, and it'll carry me all the way to molten.
I also think the Corruption's a far better counterpoint to the Hallow, and digging tunnels around its chasms is less irritating due to their regular, boxy shape. Hugging the shape of Crimson chasms is a mess, and the vines make it a bit more work to evil-proof.