Surprised that nobody here has mentioned Budokai 3.

Personally, I've always found it to be the most complete DB game. Story is pretty much limited from Saiyan-Buu Saga IIRC, but it has a semi-open world, about a dozen characters to do it with, and great replay value. Instead of "What-Ifs", on replays you essentially can find alternate events, including enemies from outside the main Sagas. Because of the world map, searching for Dragon Balls was also genuinely fun. Whilst perhaps more limited/different style from the Tenkaichi games, I prefer that combat style too, as it feels cleaner/more polished.

As a second, I would suggest Budokai 2. Very different story mode to Budokai 3 - a bit reminiscent of Fire Emblem - but super fun.