I'm not sure but I've been wondering this too

I would like to know this as well. I have neither, but I'm wondering which is the most powerful for when I have to make the big decision. I do have great waterproof toys so if the Siri is in fact the stronger rumbly toy, I am willing to give up the waterproof-ness of the Alia.

I'm having a hard time choosing between the two.

well between the two if the vibrations are the same and you like the deep rumbly frequency i'd say for 15$ the alia comes out ahead, that said since I haven't found anyone commenting on how similar they are yet if you need to be sure it has that depth then the siri is for certian, even though the lack of waterproofness is depressing. if only more people had both of them and were willing to compare them for us, but then again these aren't cheap so I see why they wouldn't

Siri and Alia have the same vibration frequency, but Siri is stronger. Meanwhile the Alia is waterproof and more comfortable to hold.