I guess the answer depends on your goal for the season. High ranking, or League success?
If it's high Ranking, you obviously need to replace Goodes, and/or possibly upgrade other spots.
High Ranking usually involves taking a few more risks around this time of the season, where as League success usually means playing it safer, and keeping at least 2 trades up your sleeve.
Basically, it's the difference between 2 trades this week, and one.
Your one trade options, which can fit a high Ranking strategy if your selection is good, appear to be (in price order):
Ibbotson - $459,200 - Has the Ross Lyon question mark hanging over him, as well as the "has he just been in a purple patch, that is now over?" question mark. Didn't start until round 5, and proceeded to look very good for a Def. His first 9 games produced four 100+ scores, and only one 80-! He averaged 103 in that time. But are there signs a corner has been turned? His last 3 have been 70, 113, 58. Also, it is interesting to note, he is averaging 108 at home, and only 83 away this season! Freo have 3 more home games to come. Risky, but so are all Defs in this price range!
Taylor - $457,200 - I'm a hater of the "If you take out these games, then he has done this" type logic. Having said that, Harry's season without his first 2, and last game, looks good! Six 100+ scores, and only two 80-'s with an average of 102 without those 3 games. Currently sitting 7th on the Def's aggregate ladder, even though he has missed a game!
Henderson - $449,100 - Gives you the poor man's DPP with Staker. I call it the poor man's DPP, because DPP links with 2 players expected to be in your 22 only cover those 2 players. Young player with improvement still to come. His role and importance has changed as the season has progressed (the only time I will allow the "if you take out" type logic). Since round 5 he has played 11 games, for seven 100+'s and two 80-'s. He has averaged 97 since he grown in importance. Some might point at Waite, and say he will/might drop when Waite returns. I think they're wrong. Waite hardly played at all round 15, so let's just look at Henderson, when Waite played from rounds 6 to 14 (excl rnd 7). In those 7 games Henderson had four 100+'s, two 80-'s, and averaged 93, so no great effect.
Hibberd - $434,300 - Big plus, he has the biggest average of all the players you can afford. Bigger minus, been in steady fall since round 11. His return in those 6 games shows: 6 scores between 74 and 93 for an average of 85. Another young player, with room for improvement. Possibly has been copping the Fwd tag lately. Either way, it's a risk taking players in steady decline.
I traded in Henderson for NicNat last week, so I am a little biased. Of the one trade options, I think he is best, just in front of Taylor.
The two trade option is not something I would do, if League victory is your priority. If High Ranking is your priority, I think you nearly have to do two trades.
It would seem downgrading Goodes to a D/F DPP is the best option, as you currently have good coverage in your Fwd and Ruck. Having said that, Bartel, NicNat, Franklin could cause problems this week, especially if Staker is swung Fwd!
I have been looking through options, of upgrading Rowe to Minson or Goldy. Or even as leftfield as Dawson Simpson! The loopholing isn't perfect, due to Nth's draw you'd only get proper loopholing in 4 of the 6 weeks. Simpson actually could be an interesting, but risky option, though loopholing reduces the risk a little. It would allow you to upgrade NicNat to Petrie (currently very high up on both average and aggregate tables!), and also allow Deledio/JPK to be upgraded as well!
I'm guessing you want to win your League first, then see what Ranking you can achieve, as long as winning your League doesn't cost you too much in Ranking positions. That being the case, I think I'd go Goodes to Henderson, or Taylor. With what is possibly going to happen this week at the selection table, it's probable you may need Staker in the Fwd's anyway.
Good luck, which ever way you jump!