naraku and I were talking about it in who knows what other thread, but the consensus is generally that the 1999 adaptation handles the first part of the series, especially the Hunter exam, better than the 2011 version. It's sort of like FMA vs. Brotherhood in that the former spends more time covering the same material and is able to pace it better and flesh it out more. In particular there was a great little mini-arc between two of the Exam stages that was technically filler but fit in really well and let you spend more time with a lot of the other candidates. There was also a crucial little piece of backstory and Gon character development right at the beginning of the series that the 2011 series skips over in favor of chucking it in as a flashback somewhere down the line. The 1999 version probably does the Zoldycks and Heaven's Arena better as well, but I'd call Yorknew City much more of a toss-up, since I really enjoyed how the 2011 version handled it too. As far as structure goes, the 1999 series concluded Yorknew via OVA (it was literally just the last 8 episodes of the arc), then covered Greed Island via a couple more OVAs, and that's where it left off. Greed Island is the only part of the 1999 series I never saw, so I can't speak personally as to how good it was.