Well, you've got some seriously different items up there. The Minna Ola is really different. It has some really innovative and unique controls. Read up on it. The Tiger and Fifi are both dual stimulators for g-spot and clit but will be anatomy and preference dependent. It looks like the Tiger won't work for women whose g-spot is very far from their vaginal opening and doesn't give you any option to manipulate the clit stimulator independently of the shaft, while Fifi will require pretty specific spacing as well as enjoying the vibes on either side of the clit, plus I've heard the vibes in the "ears" can be a little weak and the "ears" themselves are really flexible. The G-Ki is very versatile and can adjust to fit different anatomies and, in some cases, may work to stimulate the g-spot and the clit simultaneously when it's bent to the tightest angle. However, I've heard and read that it's not terribly powerful. In terms of power you're probably looking at them in this order, from least to most powerful: Minna, G-Ki, Fifi, Tiger. I think Tiger will be the least versatile in terms of working for the least number of different women, followed by Fifi, Minna, and G-Ki in that order. I would strongly consider the rest of the Je Joue line (manufacturer of Fifi and G-Ki). Uma and Mimi are excellent, powerful vibes. Mimi is a clit vibe and Uma is a g-spot insertable (Uma is the same shape as Fifi but without the "ears"), depending on what you are looking for. I've also heard that many women like Uma as a clit vibe too. I can't give you a strong recommendation for any one in particular without knowing your preferences, let alone anatomy, but these are my opinions of the ones you have listed. Good luck!