Toxic by FAR.
First of all Attract is very luck based in the sense of bar specific Pokemon like Latias whether you'll be facing a male of female is completely random. Consistency > Luck. Use your skill, don't just hope to get lucky. And Legendary Pokemon won't be affected by it all, along with a few others without genders (exceptions exceptions).
Second of all, Infatuation will reset once your opponent switches out. Toxic will remain bar moves like Heal Bell or abilities like Natural Cure. This means your opponents Pokemon will have a constant timer on. They can only stay on the field for a limited time before having to switch out. This heavily limits your opponent.
Lastly, Toxic will severely cripple defence cores. Defensive Pokemon like Slowbro rely on their heavy defences to outlast opponents and block attacks. They can't do that if they're constantly taking damage all the time and have their turns on the field limited. They can't switch in as often and are much easier to defeat.