IF you can handle the size, I'd choose Siena! Looks amazing, but it's too large for me, so I've not bought it. If the size concerns you, then I'd go with UFO. Seems like a very interesting toy, but it's too expensive for what the reviews say -- not worth the price, basically. So that's why I never bought UFO. Not sure I'd find it worth such a high price. I have Cleo, which is similar to UFO and I rarely use it because it puts me in an awkward position, but it is a really nice toy.
I own the banana and it is adorable, but I never use it because there is a painful seam down the middle. I'm not a fan of the other choices, for the money I'd look elsewhere. Based on what you have here, I'd suggest the We Vibe Touch or Mona 2. I own the We Vibe and LOVE it, but have heard really great things about the Mona 2.