"Good" is in every case just a space keeper, of course, for a differentiated description. If you percieve something is good or bad depends on your criteria on the subject. Yes, here it's enjoyment in the first place. But this depends here in my opinion on expectations, writing skills, getting me into the story, details for imagination, correctness of background etc. With this novels the series was at its beginning, it was new and, yes, I enjoyed it very much.
Now whilst you say, I want to read them again. I don't know about the details anymore (were on the first books I read) but I know that I loved them. The Space Wolves are a great chapter for their battle doctrine, behavior and organization. But I'm reading the books in German if can and Sons of Fenris and Wolf's Honour aren't translated yet. That's why I'm waiting patiently in hope. I voted Dorn for "best primarch" because he fits most to my own (concept of a) chapter .
Ok, but read them in english then? I think you should do that, sure it might be hard if you don't have english as your first language. Its same for me. But the more you read, the more you learn. And Dorn is awsome indeed! I like him! Not more than Russ ofc. sure, he was not perfect, he let his anger control him, from time to time. But that's the way of the wolf it seems. But his love and respect for the emperor and his children was always there.
Maybe I should really do it. It's just a collecting thing. But I could read them and buy the translations for the bookshelf afterwards if they'd come.
Magnius pre-Fall he and his entire legion could have been the most effective demon fighters/hunters had the Emperor and Russ not been dipshits(don't get me wrong love Russ all time favorite Primarch) Then again Angron is quite possibly the most tragic and badass Primarch half dead and he held a fucking Titan up on his back for an extended period of time.
Vulkan Whilst he was a genetic Demi-god, he never lost sight of why he was created. To be a guardian and protector for mankind as well as a leader in the great crusade. He always put protecting the weak his priority and his legion have inherited this. If any chapter can be described as "heroic" then it's the Salamanders. Sanguinius was the most martial and even Horus admitted he was no match for him one on one. Well until he was corrupted at least. I see many have said Fulgrim because of his ability to kill other Primarchs. However I disagree, I think he was one of the weakest. Who fell to Chaos quite easily and was possessed by a daemon prince when he murdered his brothers. An act he couldn't have done had he not been so in my view. Angron I think is very misunderstood and had not the Emperor betrayed his wish to die by his friends side would never have turned to chaos in the 1st place. All the Primarchs have their strengths and weaknesses, so deciding on a "best" really is too basic a question. The best at what ?