It's no secret that Green Lanterns is probably my favorite DC title being put out at the moment. However, there is this weird thing where no one issue is so good as to go up higher on this list (there are other series I adore that missed these lists for the same reason). Green Lanterns managed to make it primarily for this issue, Green Lanterns #29 by Sam Humphries and Eduardo Pansica.
This issue is one of the issues that really shows Simon Baz and Jessica Cruz growing into their own as characters. Where they came off as the gung-ho rookies inexperienced with the Green Lantern Rings in prior issues, here they are responsible for training new Green Lanterns in the way of the light. If they fail, the Lantern can perish from the overload of willpower.
Simon and Jessica both are easily among the most likable characters in DC Comics, and both use their strengths to their advantage in this comic. Jess is kinder and more understanding; Simon is harder on them and more headstrong.
The six Green Lanterns they train here are had been given distinctive identities and personalities leading up to this issue, and they were expanded upon in this comic. Each is memorable, likable, and has their plans for the Green Lantern Ring. They're not inherently selfish or bad; they just have more priorities than a vague celestial threat on a world of which they've never heard.
Eduardo Pansica downright incredible artwork helps bolster this comic a lot too. The textures, forms, and expression of the world he depicts is breath-taking. Julio Ferreira's inking is top-notch, too, and Blond's color work keeps things bright and lively.
Tim Seeley took over the book not long after this, and Green Lanterns is still one of the best books on the shelves. However, when I think of the best issues of the series, Green Lanterns #28 is one of the first that comes to mind (the others came out before I was brought on to Bleeding Cool).