We have the Sarticus one with the silicone ball but in the large ball version. I love it. I like that it buckles in the back and has snaps in the front. It lets you pull it off real quick if there's an emergency and you need to talk without having to fumble with a buckle.
We also have the fantasy gag
which has a penis shaped gag and I love that one too, but I think it can trigger a gag reflex in some people, so it might not be the best choice for everyone.
I really like the aslan pink one too, but but I haven't tried it because we just have the two gags and probably won't get any others. I do think it is darling though.
I would say you probably can't go wrong with the aslan or the sparticus silicone ones, it might be a preference of which you like the best. Rubber ones are going to taste like rubber, so you'll have to decide if that's something you like.