Well, for my "general" friends that like anime, I'm ashamed/embarrassed to introduce to them any show that has ecchi, even if it's a show that actually has good animation, plot, etc., but really just included fan service a little too much. I tried introducing a show to a "general" friend once, and he wouldn't stop saying that I like perverted stuff to my crush/es (the horror!). I also don't recommend cute/moe shows because they're usually more knowledgeable that I am.
I really liked A-channel, Acchi Kocchi, and K-On!
Although, if I were to really single one, it'd be Senki Zesshou Symphogear. Usually guys don't watch them, and they should never ever tell anyone about it. Else, people might judge. Well, except for you guys!