Seven of Nine is the best. I love her outlook, her strength and flaws, and pretty much any episode that centers on her. You mentioned that you liked Tuvok-Seven: I think one thing I like is how she can be a foil for all the preexisting characters, and yet she most certainly has a character and flavor of her own, as well.

I probably said this earlier about Kes, but I was deeply disappointed in what the writers did with the premise. They had made her have a lifespan of just seven years, so presumably they could have done things with someone who lives life vastly accelerated (compared with humans), and I guess they sort of tried (having her get pregnant, showing her old in (oh: that's a special return-visit episode in a future season...), but I think they could have really leaned into that more and done more with what it means if one person's lifespan is so out of sync. So I was VERY happy to get Seven of Nine as a replacement. Seven managed to be intelligent, strong, and yet vulnerable in a way I really enjoyed.