Unlike your standard VPS hosts (DigitalOcean etc.), a good seedbox host will take your inevitable DMCA notices and file them in the shredder.

Basically, you'll find ones with fast storage with big storage for reasonable prices and that are... explicitly sanctioning this use case. And I'd bet the competent ones specifically design their network and client settings for good performance. In professional settings getting good large storage performance is sometimes a struggle or expensive.

I've thought about using them for non-shady data storage and transfer given the price and performance. Nothing sensitive which wasn't encrypted, obviously.