The Hitachi. I wouldn't care about discreetness. I like it too much, and if you're going to go with a toy you might as well go all the way, and you can say it's just a body massager. I've been slightly interested in the discreetness of kegel toys, though lately
The first one DOES NOT stay closed. It's not discreet to have to fish around your purse for your bullet because the case pops open every few minutes!
I'd go with something else. The Mood Powerful Small and Ammunition are very small and can be stashed away, and I'd even recommend one of the Key Charms over those two!
My Lelo Mia used to be my "purse vibe," because it's small, discreet, and charges via USB so I can take it anywhere.
However, nowadays I'd probably say my We-Vibe Tango. It looks like a weird blue lipstick, is small enough to easily fit in even a tiny purse, and has amazingly rumbly vibrations. The only issue is that it doesn't lock for travel, so I'd have to stash it in a glasses case or something.
Neither one of those toys appeal to me at all. I have been known to drop my tango or mimi in my purse on a date. I have been eyeing the lelo mia 2. I think that might be a great gift. I just haven't tried it myself yet.
The necklace bullet. I have the pirate one and wear it all the time, not that it works anymore but more like, "my dirty little secret". It makes me feel I know something the rest don't know, like I have one up on them. For some strange reason I don't feel nervous when wearing it, just the opposite.