Paralyzing is worse IMO. You lose 1/4th of your speed effectively making you slower than like 95% of your opponents. That and you have a 25% chance of losing your turn. Poison is better against tanky pokemon that are hard to take down through just attacking.
Poison is more useful when you're the one poisoning but being on the receiving end paralysis is worse. Slowly chip away at your opponents HP (especially if they have some insane defenses) but when you paralyze them it hardly does anything besides slow them down. But when you're paralyze it's like 9/10 you can't attack but when your opponent is paralyzed 9/10 they can run a marathon, do a backflip, and lift a mountain.
Paralysis by far, especially with a Paraflinch combo using moves such as Air Slash. Toxic is deadly, but there's no chance of the opponent not being able to attack you, which makes it all for naught if not used early on.