I own three toys: a glass dildo, a fairly basic vibrator, and a silicone dildo that I still need to get a harness for. None of them fit inside me. I’ve used the vibrator externally and had some fun with it, but this question is only interesting for me if I interpret it as “what’s your favorite toy to use on other people?” because that’s most of my experience with toys.
So: Definitely the silicone dildo. Sparkly really, really enjoys it, and I don’t have to be as careful with it as I do with glass or hard plastic. And I’m really looking forward to using it with a harness.