You're asking for a perfect system and there isn't going to be one
Correct, I've said that many times. There is no perfect system, everyone is going to have a problem.
The best playoff system is one where we take the top ranked teams.
Again, how are the teams "ranked"? It's easy to say "take the best" or "take the top ranked". If that is the only qualifier, it remains extremely subjective.
TReally there's probably only 3-5 teams really deserving, but if we're going to 8 then that's what we have to work with. Why are you talking about changing the number of playoff teams each year?
I talk about changing the number of playoff teams each year because others keep posting about the number of "deserving" teams and that "undeserving" teams shouldn't be in the playoff. If you want to keep "undeserving" teams out, you would need to trim or expand the field size to match the number of "deserving" teams. I don't like the idea, but I keep posting it to show that with a given field size, there will likely be some "undeserving" teams in the field some years and "deserving" teams left out of the field in other years. Rarely will the field be the "right size".
Yes there may be some bias, but if you're arguing to get that 8th & final spot then you're probably not that deserving to be in the playoffs.
Agree. But if you're arguing over the 8th and final spot and neither team is "deserving" as you say, why is a committee, poll, etc., needed to make that determination? Pick an agreed-upon metric that is uninfluenced by anything off the field (ie, ignore historical performance, TV viewership potential, etc., keep it to something tangible accomplished by the teams) and don't waver for it. When there is a committee or poll involved, there is bias, whether real or perceived.
Another example is 1996 season. How can anyone believe that #20 Texas at 8-4 would be more deserving to be in an 8-team playoff than #6 Nebraska because of one game? But I can justify keeping 2 of these 6 teams out of the playoffs (BYU, Nebraska, Penn St, Colorado, Tennessee or North Carolina) by using strength of schedule & how you win/lose games as the next metric. Could there be bias on my end on choosing 4 of those 6 to be in the playoffs? Sure, but I can also justify my decision using SOS, etc as long as I'm using the same reasoning for all teams. Voila, you have your 8.
I think I can come up with more real examples where having a Conference Champion as an AQ for an 8-team playoff be worse than selecting the top 8 ranked teams.
There are plenty of examples where conference champion AQs would produce a "worse" field than the top 8 "ranked" teams. That's not my point, which is every team should have an objective path to qualifying for the playoff. P5 AQs won't eliminate bias from the playoff field completely as there will still be 3 at large teams with which a potentially non-objective metric will be used to select. However, it assures every team in an AQ conference that a pollster or committee (or a metric they create) won't keep them out of the playoff if they win their conference.
As you say, "there's probably only 3-5 teams really deserving." I believe it could be reasonably assumed that at least 2 of the 5 AQs would fit into the "deserving" 3-5 teams, and with 3 at large spots, the other 1-3 "deserving" teams will also be in the playoff field. Voila, you have your 8 and it includes your 3-5 "deserving" teams while also providing an objective path for all AQ conference members to qualify for the field.