This is tough.
As often written by many people here, first half of season 9 was incredible, so emotional, so bold. The way it was filmed, lighted and edited was fresh air after dull season 8 and new and creative. Have you ever seen Miss Elie and Clayton, or anybody else having a breakfast on the terrace in such a panoramic shot ? Never seen ever after. "Wind of change" is a true masterpiece, in every way. Susan Howard deserved an Academy Award.
But its second part is boring routine unfortunately... Storylines and characters drifting on a road to nowhere... It's night and day.
The structure of season 10 is obviously stronger. Sort of. They seemed to have a clear vision from A to Z. The whole season was shaped as soon as the first two episodes aired. Everything we were going to witness was linked to the genesis of the season. The Parmalee plot, the Calhoun plot and the death of Ewing oil. But, let's be honest, the Parmalee plot made no sense. All evidences (X ray stuff and everything else) prove Parmalee IS Jock. But, against all odds, he confesses his lies to Miss Elie. OK.
Then, we've got the A-Team Calhoun plot, John Ross being rescued. No surprise. Everybody is safe.
The loss of Ewing Oil remains the best part, leading to the cliffhanger.
Two seasons, good and bad things in both one...
But, if I had to vote, I would root for season 9. Linda Gray's performance is amazing. It's beyond acting...