Gigi and Mona have the same kind of vibrations. I imagine that Liv would be the same as well. I have seen people say that Siri is stronger, but it feels weaker to me. The vibrations seem to be the wrong pitch for my body and feel like they are too slow and flat. Ina has a shaft like Mona or Gigi, and clit vibrations like Siri.
I haven't tried the Insignia line. According to Splendwhore in
this thread Alia and Siri have the same vibrations.
I also haven't tried Iris or Elise, which have dual motors. I think Carrie Ann owns every Lelo toy, and according to her
Elise review, it has stronger and deeper vibrations than any other Lelo toys she's tried.