Well, it may not be best to compare vaginal toys with anal toys. They are two different experiences, after all, and anal really needs to be something you're interested before-hand. Out of those two, I'd lean towards the balls - but that's mainly because I'm not liking the look of the plug. A nice pyrex one, like the Moonshine, would be worth the money. As for balls, I'd recommend some smart balls. Those are a pair of balls, attached by rope of a metal bar, with a moving substance inside, like sand, usually - or even smaller balls. Try exercising with those inside you and you'll be driven crazy!