The most popular currently being Batman, from the success of the recent Dark Knight movie. In addition to the Batman action figure, you could also purchase the Bat-mobile or a villain to go with, such as the Joker. Junior action hero collectible figurine are also popular action figures. Toys can be purchased at large toy shops, which is recommended if you are looking for a wide selection.
Spider-man and many Spider-man villains can currently be purchased from any toy shop. Superman is not as popular right now, so he might be a little harder to find. These can be a really fun toy for young boys since there are so many different ones to collect. This includes Darth Vader, Storm Troopers, Luke Skywalker, Han Solo, Chewbacca, Obi-Wan Kenobi, Anakin, an Imperial Officer, Yoda, Princess Leia, and Avengers Figures.
One of the top selling action figures on Amazon avengers hot toys action figures. This action figure is geared towards teenage girls. Girls are generally more interested in dolls than action figures, but when movie characters are made into action figures, girls may be interested.