I've seen everything, but some things only once, so my knowledge on them is fuzzy at best.
The Dragon Ball movies are okay, I suppose. The dub for Movies 2 and 3 are terrible (assuming you watch dubbed), Movie 4's script is about as accurate as the Cell/Buu arcs of Z (FUNi) and GT. Movie 1 however is better quality than the rest, like Kai compared to Z.
All of the Dragon Ball movies are pretty much just re-tellings of the original story, not new original plots. If you're going to watch any, I'd recommend 4 personally.
Other than that, you wouldn't be missing out on much.
World's Strongest is boring to me, the Bojack Movie is alright, the Bardock special is good (the first one at least), 2008 OVA I don't remember much, I don't recall disliking it. And the Hatchiyak special, I didn't pay much attention to, so I don't remember much.