Fusion Reborn is EASILY the best Dragon Ball movie so far. It has pretty much everything you could want from one of these.
Taking place somewhere within the Majiin Buu Arc, this movie centers around a disaster in the afterlife. Havoc breaks loose when the culmination of evil thoughts of all humans is concentrated into one being: Janemba.
Transforming the arena into a colorful array of jelly beans, this creature at first seems quite harmless- but back on Earth, the imbalance causes the dead to rise. Old villains return for more, like Frieza (and HITLER???) while Goku fights the reality bending blob.
The fight sequences themselves in these movies are really nicely done, and flow well. Janemba can create portals and basically camps Goku. It really kicks up when Goku transforms into SSJ3- and Janemba gets a transformation of his own. Phasing in and out of reality, he wields a blood sword and pushes Goku to the brink. The last section of this movie involves biding time as Goku and Vegeta attempt to get their fusion down right. When they finally do, an epic conclusion sends everything back into place.
This is also the best looking movie since Dead Zone and The Worlds Strongest (some really nice thick line-art). I personally loved this movie, and trudging through some of the more tedious films in this franchise was well worth it. It's comedy is pretty on point with Goten and Trunks, and there's some pretty cute moments with Videl and Gohan. Overall I highly reccomend!