I like them both. There's issues about both that keep me from really "loving" either.
I LOVE the Mimi's strong strength and deep vibrations, but the buttons drive me nuts. (The buttons don't bother the boyfriend though, so it might be a personal preference). The buttons are flush with the toy, and it's hard for me to get any 'feedback' about whether I pressed each one when I did
I LOVE the features, the controls, and the shape of the Zini Seed, but I didn't feel like it was strong enough for me. It had moderate vibrations, and I would have loved more.
I wish I could meld the two together. I'd really LOVE that toy. Strong vibrations like the Mimi and control and shape like the Seed.