Originally Posted by
Crazy Diamond
A good chunk of it was retconned or written out during Johns's run but if you don't care about that sort of thing here's some stories to start with:
The Road Back
A Guy and His G'nort
Mosaic
The issue where Alan Scott came back I remember being alright
After issue 25, Gerard Jones (the writer who started vol. 3) became more inconsistent as a writer but the following story was alright:
The Third Law
For Spinoff titles, I liked Mosaic and Green Lantern Corps Quarterly. Guy Gardner was alright but it depends on how much you like humor in your comics. The series takes a different direction around issue 22 when it becomes Guy Gardner: Warrior. It had one of the best takes on Guy but some readers couldn't get past the new powers he got. Also had a great supporting cast too along with Guy opening a bar.
As for Kyle's run, a few parts in trade. Here's what I've read:
Emerald Twilight/A New Dawn
Circle of Fire
The Power of Ion
Emerald Knights (Kyle meets pre-Parallax Hal for the first time though don't see how this story still works after the Parallax retcon)
Green Lantern/Silver Surfer
Baptism of Fire
Of those, I liked The Power of Ion the most. Emerald Twilight is important due to how it led to Kyle's introduction and Hal becoming Parallax, but opinions vary on how good that story is. I would read that too and decide for yourself.
Overall vol. 3 was pretty good up till the last two years of the title. If you see anything with Ben Raab, I would skip it. Apart from Amon Sur his run was pretty boring and he turned Kyle into Hal-lite. I also didn't care for Kyle flying off to space near the end.