Saiyan/Namek Goku, Andriod Saga Gohan? I think Gogeta and Gotenks should have separate spots, since they are their own characters and will have their own accessories. Goten and Trunks with have regular and SSJ heads and Gotenks will have regular, SSJ3, and SSJ. So that would be 9 spots. I don't see Gogeta coming, but it's a good choice. He was only in the movie for less than a minute, but people love him. If you look up figures reviews for past figures he has a lot. The same with SSJ4 Goku. Broli and him have more views than anyone in the series! Not so much with Tien and Yamcha. I think Tien has such a simple design, that it doesn't appeal to people much figure or fight scene wise, except for his fight against kid Goku, but I think it's for Goku, and it's not that many views. I was just looking at the views for the video games, just typing their name in seeing the view count first videos showing up, looking up popular/favorite character lists, and figure reviews for past releases. Not the best method, but I thought it would be helpful.
I would argue Bardock for the amount of specials he's had, Toriyama's recent expansion on his myths with his wife and the Saiyans, him being a pre-order incentive for the new Battle of Z game, and he and Broli are in the video games even when there's very limited characters (Just Saiyans and big villians).
Broli has to be big in Japan. He had 3 movies before Funimation brought the movies over and was popular in the West, when people were just watching bootlegs in Japanese online. Maybe that's why the origin didn't bug a lot of people, because all they saw were the visuals, emotion, and music. I'm not bashing it, I'm just giving one of the explanations why he's loved. All people saw was a monster Saiyan massacre their heroes, in what was to believe their most powerful forms. He's had multiple forms in video games even SSJ3 and is in the animatic intros for the games.
There's been really popular DBZ games that are Japan exclusive or don't come to the West until much later. Right now there's the J Stars Vs and Dragon Ball Z Zenkai Battle Royal that people have been petitioning for a long time to get here.