I'm just going with the OP.
The best 22 we put out on grand final day was arguably 2019. That team won the last 12 in a row, culminating in an interstate qualifying final win, a tough, come from behind, injury-struck win against the second-best team in the prelim, and a dominant performance on the big day. You could argue the 2020 side was the best, and it certainly climbed the highest mountain.
Changes from one flag to the next:
2017-19
Out: Rance, Townsend, McIntosh, Butler, Grigg, Graham
In: Lynch, Bolton, Baker, Pickett, Soldo, Short.
Even without Rance I think the 2019 side was stronger.
2019-20
Out: Caddy, Ellis, Soldo
In: McIntosh, Balta, Graham
Line-ball.
From a starting point of:
[35] Nathan Broad,[18] Alex Rance,[2] Dylan Grimes
[14] Bachar Houli,[12] David Astbury,[1] Nick Vlastuin
[33] Kamdyn McIntosh,[9] Trent Cotchin,[21] Jacob Townsend
[23] Kane Lambert,[4] Dustin Martin,[22] Josh Caddy
[27] Tom Lynch,[13] Taylor Walker,[3] Riley Knight
[40] Dan Butler,[8] Jack Riewoldt,[17] Daniel Rioli
[25] Toby Nankervis,[3] Dion Prestia,[6] Shaun Grigg
[5] Brandon Ellis,[10] Shane Edwards,[34] Jack Graham,[46] Jason Castagna
from our era of 17-20 (including 18) i reckon our best 23 were:
[35] Nathan Broad,[18] Alex Rance,[2] Dylan Grimes
[14] Bachar Houli,[12] David Astbury,[1] Nick Vlastuin
[33] Kamdyn McIntosh,[9] Trent Cotchin, [5] Brandon Ellis
[23] Kane Lambert, Tom Lynch, Shai Bolton
[17] Daniel Rioli, [8] Jack Riewoldt, [4] Dustin Martin,
[25] Toby Nankervis,[3] Dion Prestia,[6] Shaun Grigg
[22] Josh Caddy, [10] Shane Edwards,[34] Jack Graham,[46] Jason Castagna, Jayden Short
It hurts to leave out Baker, but his best footy came from 2020 onwars. I reckon all those above were valuable for at least 2 season between 17 and 20.
Balta likewise misses out cos he really only played from 2020.