Hello.
When I learned that the manga is returning after a lengthy break, I considered starting HxH. I have watched several episodes in the past, but right now I want to watch them all again. What variations do you guys suggest? The 1999 version, the 2011 version, or the original manga?

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Watch the 1999 anime till Yorkshin city arc. Then watch the 2011 anime till chairman election arc. And then pick up the manga from Dark Continent/succession arc.

The manga is the No 1 choice. The digitally colored version is fine if you really need colors.
The anime is best enjoyed through the end of the Yorkshin arc (OVA 1) in the older version. Switch then over to the Madhouse anime. The Greed Island portions of the older show are messy and have problematic animation despite covering it with more episodes.

The 2011 anime butchers the Hunter Exam arc in places (Vol 1 to 5) so read those at all costs if you want to go with the 2011 version first.

PS: There was an OVA in 1998 before the 1999 show began. There are 3 ways to see Chap 1-2.
https://hunterxhunter.fandom.com/wiki/Hunter_%C3%97_Hunter_Pilot_OVA

I also read EU/US comics and am a librarian.
Manga-Masters, My ANN-Lists + Imdb