Apologies in advance if this answer is more annoying than helpful!
I really don't know, and my wife doesn't like inserting any toys, so she doesn't know. I could throw out a guess, but I really don't know what you like: size, materials, price range...
BUT - I can give you a "teach a person to fish" type of answer which I HOPE will help. Try starting here: link
You can sort by ratings, or price (etc), you can go to the left side of the page and choose only the size(s) and material(s) you like and you can hide the out-of-stock products. This SHOULD give you a pretty good shortlist of contenders, hopefully of no more than 3 or 4 toys. My advice then would be to read the reviews of those and then either go with your gut/heart - or post another comparison poll if you're stumped. This process has worked REALLY well for me many times.
I sincerely hope this helps!