As well as bad drawing can ruin the best stories XD I mean compare it to making a movie.
The best source material can't survive a bad script, a shaky camera and the monster played by a guy in a rubber suit.
But well not going by the stories themselves but about panel arrangement and choice of scenes, Dragonball is a very good example for mangas (well Akira Toryama is definately a pro, and the manga is famous for a reason.)
For the European comics I'd say Asterix, Tintin and Jeff Jordan comics are standing out most to me. Asterix, cause well at least teh old ones got all the mixtures right introducing the setting, never too much text warring with the art and a great flow between the scenes.
If you for example compare them to the Blake&Mortimer mystery comics, those have good story, good art but they are buried under giant speechbubbles and explanation boxes.
Tintinis especially eye catching to me because of the background art, every place seemed to have its own personality. (That is some tip for drawing BGs I heard somewhere btw. treating the BGs not as neccessary evil, but as an additional character in the scene.)
Jeff Jordan is a detective comic as well adn not as well known as the others. The artist who made them was not exactl the fav of their editor and the comics sometimes suffered for that (like 'make that story shorter', 'the characters don't look cartoony enough' - well you get the idea) makes me wonder what masterpiece we missed out on because of that editor, 'cause they are still above average good.
Though I went and checked, they use different size but square panels mostly and I couldn't see any big differences in the gaps in between those panels for Asterix or JJ.
Playing with the gaps for scene flow seems more common in american comics I got some old Conan the barbarian comic album laying around that has that feature, well that is a case of panel-technic beeing better than the related story or art.