I didn't say that Summertime Saga has a better art style than SoC. I said it has an "extremely inviting" art style, biiiig difference. Summertime Saga, for better or worse, is extremely consistent, well drawn, has a lot of variety in character design, and it's bright, cheerful, and fun. Whether you like it or not is irrelevant because it is objectively good, it's just not complex or particularly detailed. It's also a completely different genre. Using manga as a comparison point, Summertime Saga is One Piece and Seeds of Chaos is Monster. Both have very different art styles, but if someone told me Oda's art style is bad I would laugh... and not in a way that indicates I think what they said is funny. They would be the object of my laughter, it would be cruel, derisive, and insulting laughter. If you told me that Naoki Urasawa is a poor artist I probably wouldn't laugh at you, but I would certainly dismiss your opinion on pretty much everything. SoC's art style is not better than SS's, it's just different.