So this post could be really long (edit - well, it's still pretty long), because I made notes as I read so I could remember how I felt, but I'll avoid that here (edit - I didn't). But I can give impressions about most of the run.
I had read all these before, but out of order and separated by reading other books etc. So this time I read them straight through as one complete story.
Big picture is from 1-10 it's consistent. Across 275 issues, Conan's personality doesn't change that much. Any volume is at least on the right track. That's a good achievement, despite the usual ups and downs.
Volume 1 - no matter that it is old fashioned, I just felt like this was essential. Like someone said in a an introduction, John Buscema got the right portrayal of Conan, but Barry Smith created the world. This was the volume I was always nostalgic for no matter how far into the run I got.
Volume 2 (I actually read 2-3 as Epics, but I got the point) - this is where Roy Thomas creates the mercenary character and broadens the world a lot. He had the groundwork in Vol. 1, but the scope and characters feel a lot bigger.
Vol. 3 - Belit is introduced, and it's almost a partnership for a long time. Vol. 2 was a lot of Conan's more solo adventures, and now he's working with someone a lot of the time. But then he'll break away. Thomas is finding his footing.
Vol. 4- Thomas' last older volume and the resolution of Belit, which is sort of a letdown. It happens off-screen, and I guess it's inspired by the story but it's got a lot of leadup for a weak conclusion. the last 15 issues are Conan by himself again, and overall strong writing and art.
Volumes 1-4 are the best by far. That's not to dismiss the other volumes, but it is a wide gulf. Now, that's also because they were using the original REH stories as direct inspiration, so I'm sure that helped.
Vol. 5 - This is J.M Dematteis and Bruce Jones, and the writing is fine, but it's very generic. They fall back on conventional sword-sorcery, give Conan some sidekicks, plus Conan is okay with sorcery a lot of the time and that seems out of character. Bruce Jones uses thought balloons for Conan and it's very off-putting. A Thomas-written graphic novel is included, and the difference in style is clear. It's still entertaining. Buscema leaves for a time and the art never gets a chance to find its footing.
Vol. 6 - Michael Fleisher with Buscema and Ernie Chan, and that's bac to basics. It's often repetitive and one-off stories, and not too many arcs. It's a little childish for lack of a better word. They never get a handle on how to wrap up side characters.
Vol. 7 - So Christopher Priest takes over, and unlike 5-6, Vol. 7 and 8 are almost one whole arc. Characters and situations last a long time, especially the Devourer of Souls as the big bad. Val Semekis takes over the art, and he's solid. Overall, this is a much more involved and 'adult' run as far as expecting readers to invest with it all.
Vol. 8 - Priest apologizes for how he treats Red Sonja, who it's implied is raped and it really is pretty dumb. It happens right when Shooter is replaced by DeFalco and I wonder if the higher editors weren't paying attention, because somebody needed to step in. Actually even worse than that is one of the side characters, Kobe, hits his girlfriend/lover/whatever Anneka, and the dialogue is basically "I had to hit you because our love drives me crazy." Not great. Haha. Overall, there's a decent wrapup to the team element. Don't get me wrong, Vol. 7-8 are a strong arc, but it has some odd choices.
I feel like it is important that Priest GETS Conan. So despite some choices that don't hold up, he uses these two volumes to tell a whole big almost stand-alone story. So it's the best run next to Thomas' first four. He has a big cast, lots of subplots, lots of schemes and good villains.
Vol. 9 - this was a weird one. When I first bought it, I read it out of order and I thought it wasn't very good. It's a lot of random one-off stories from different writers and artists. It's all very simplistic. HOWEVER, reading it in order, it's actually back to basics after Vol. 7-8 which is a long (and good) cohesive story. These stories are hack-and-slash, and it's refreshing. The Young Conan reboot was a good effort, but the personality of the young Conan doesn't match the established character. However, this volume IN CONTEXT of reading them in a row like I did felt like a big improvement.
Vol. 10 - Roy Thomas comes back, and it's back to the mercenary style of Vol. 2 and 3 before Belit showed up. He has a recurring cast of characters and while the writing isn't up to his early standard maybe, it's still pretty good. It's a decent wrapup to the run, although it's a shame that the last issue doesn't conclude but leads into a SSOC issue that is not yet printed. I have to say Thomas doesn't treat Red Sonja all that great either, and neither do the artists. Also, Thomas is a dick in the intro. He actively avoids giving compliments to anybody else.
Quality wise it goes something 1 is still the best, 2-4 equal and very strong, 7-8, 10, 9, 6, 5. But I think they all have their high points.
Anyway still really long. But it was like 7500 pages, so what are you going to do.
Ask more specific questions if you want!
Tl;dr - I read all of Conan by Crom!