GT could be easily adapted to make it greatness...
Have uub be a bigger contender
Less focus on pan
Don't make trunks a complete **** up
have trunks and goten fuse in teenage form
not have goku turn into kid but have the teenagers (goten, trunks and lil pan) go on voyage for dragonballs while others train on earth.
Have future trunks come back to merge with real trunks to form super trunks and take on super 17.
Have the seven dragonballs actually be serious threats and entities of the space located dragonballs, not the earth ones...
Goku and vegeta should only come back to take on ooo-shenlong.
Bebi should work for shen long and want revenge against the saiyans so goku and vegeta struggle to reach super saiyan 4 with tail additions BUT this time, Vegeta gets there first and takes on bebi and wins (bebi is in Goku's body as goku is the strongest).
gotenks, uub (super uub) and gohan and future trunks take out other six dragons either individually or in pairs.
goku makes it to super saiyan 4 and fuses with vegeta to take on omega and nearly win (not being cocky but proper all out fight).
Omega merges with other 6 balls just as super saiyan four runs out. both are mortally wounded...
just as all hope is lost, goten and trunks fuse and get his with bloodswave amplifier turning gotenks super saiyan four and he's PISSED. He completely ****s up omega and destroys them.
We go back to goku and vegeta, vegeta feels proud he ACTUALLY was the strongest in the end over goku after all those years BUT they are both overwhelmed that they know that their children had surpassed them and earth was left in good hands by the z warriors and they both perish.
skip again to the future and we see descendants of both of them in a fighting tournament. We then scroll over a crowd and notice a lot of similar personality traits to the original z fighters and here one of them say they've been giving permission to leave the other dimension for a day to see the fights. Although in disguise, vegeta, gohan, goku, picollo, chi chi and bulma are all recognisable and it ends with their kids about to go at it.
I would also throw in a love interest between one of goten and vegeta's daughter bra with the birth of their child having long golden super saiyan hair and this being the legendary saiyan instead of brolly, hence tying the bloodlines together. It would also give gotenks more of a reason to fight.