These two are quite the same but represent different statuses. Sleep is much worse that paralysis because the latter doesn’t cure during the battle if you have no certain abilities or moves. It also has a bonus speed drop on and it’s going to be much easier for you to take out your target. Sleep may wake up at any time in 5 turns but it still won’t be useful. As for me, paralysis is much better in the long run but if you want a quicker result, use Thunder Wave because it’s more effective than Stun Spore, for example.