Out of the ones that my BF and I have tried, there are two that stand out: one is wireless and the other has an attached cord. The wireless one is shaped like an
elephant and has a really great angle for clitoral stimulation. There are also little nubs that massage the labia during IC. It has some stretch, but isn't super stretchy like the ones you usually find in adult stores, keeping it from being really tight. The ring portion is made to fit enough around the shaft to hold it in place, but I guess it really depends on how wide your penis is. My BF said it didn't do much for him (he doesn't personally notice the vibration - some guys do, some don't) but I REALLY like this one, it feels incredible.
The other one is the
Diving Dolphin which has two bullets, each that have their own control lever. It is much more powerful and he notices the vibration on this one. This ring isn't really stretchy much at all, and the hole is smaller than the elephant one. So, this is a little more snug, but still not super tight (no ER visits, thank you). Anyway, the dual vibration is nice and the dolphin nose is just high enough to hit the clitoris. Great for WOT, too.