Out of all the statuses I'd definitely say that Confusion is the cheapest tactic in the book. Love (Attract) is the second most annoying status.
Those two are the most annoying because they carry a 50% success rate, so half the time you're dead in the water.
The third most annoying is Badly Poisoned (Toxic and it's family of moves). Not only does this do general poison damage, but it also doubles the damage it does each turn. I'm not entirely sure if post Gen III made it possible to be Badly Poisoned anytime something inflicts the Poisoned status by random chance or not, but more often than not I see this flavor of poisoning...and this one is a SERIOUS showstopper if you're in a competitive mode battle where you can't use items in the bag. :/
Paralysis is the final of the worst, even though it's only 25% chance...because it tends to kick in at the worst of times.
Any possible combination of the above mentioned statuses REALLY sucks.
The rest of the statuses, are thankfully too rare, as in there aren't enough moves that guarantee to inflict them. Like Frozen, I've not yet seen a move that will certainly Freeze, though there is one for Burn, Sleep, Paralysis, Poison/Badly?, and even Confusion. Where the logic in no instant freeze inflicting moves is, I don't know.