Now you may have heard the term "FanonDiscontinuity" on TV Tropes. It means you put a certain sequel, episode, arc, etc. out of your "headcanon", like people do with the Garlic Jr. or Buu Sagas of Dragonball Z, or all the Halloween movies starting from Halloween 4 (3 isn't counted here because it is non-canon). I myself have done the two holiday episodes of Pokemon because they're out of place (besides Snow Way Out was too depressing), and although I haven't done so yet, I sometimes consider doing it for Seasons 7 and 8 of 24.
This was easily my least favorite season. First, Bill Buchanan dies, one of my three favorite characters. But another of the three, David Palmer, dies in Season 5 so that's not too big an issue exclusive to Season 7.
Second, the whole "Disbanding CTU and putting Jack on trial for torturing terrorists". I can understand where they're coming from there, but that wasn't a problem in the previous seasons, why start at the point when Jack had to choose between torturing a terrorist or letting innocent people die? They probably were just pandering to the complainers (which they never did for the fans with Mandy in Seasons 7 and 8), even though Renee later tortures Alan Tanner and Alan Wilson.
Speaking of Alan Wilson, so he was the highest figure in the conspiracy? Didn't they establish it was Phillip and Graem in the previous two seasons? They just threw him in to give Tony a reason to seek revenge since Phillip and Graem are dead as of Season 6.
Most importantly, Tony turning evil. They even brought him back from the dead (which they avoided in Season 6) just to do it. They make you hate him. And he doesn't redeem himself. I hope he does in Live Another Day, but he didn't seem like he would last we saw him, and they haven't even confirmed he'd be in Live Another Day Yet. I'd have preferred if he stayed dead in Season 5, atleast Palmer remained a good guy to the end, and Bill took it a step further with heroic sacrifice.
While Season 8 was better than Season 7 IMO, there were two plot holes they never addressed.
First, Logan's still alive? Logan died in Season 6. He got an artery cut and he flatlined. Doesn't a flatline mean you're dead? They never explained how he survived, he was clearly intended to die in Season 6.
Second, Suvarov's evil? After the whole thing in Season 5 he seemed like a good guy and made the peace deal, and in Season 6 he was only protecting his country. So why is he helping terrorists and acting as final antagonist alongside Logan?
Why Season 6 would have been a good ending
Because there's no cliffhanger like Season 2, and Jack doesn't have to go on the run like in Season 8 (and Season 4, or get locked in a prison like Season 5). All the major antagonists, including Nina and Cheng (but excluding Mandy), are either dead or imprisoned. Logan was redeemed but presumed dead, and last we know of Tony, he died the character we love.
Also Seasons 7 and 8 were the ones where they intended to bring back Mandy but didn't, a symbol of how they go out of their way to avoid pleasing fans.
Anyway, don't get me wrong I still love the series especially Seasons 1-6, these are just my complaints specific to Seasons 7 and 8.