"Halloween II" (1981) is basically my favourite slasher movie of all time and personally I'd even take it over the original.
I also like Rob Zombie's "Halloween" films very much; not neccesarily the way I would have "rebooted" "Halloween" myself, but Zombie's take has quite a stylistic punch, with some of the death scenes being far more emotionally involving than in the original series.
"Halloween 4" is basically the sequel which came out when I entered horror fandom in my late teens, I even caught it on the big screen back then, so in that sense it'll always have a special place for me- though I was somewhat underwhelmed when revisiting it this Halloween.
"Halloween 5": Powerhouse performance by a very young Danielle Harris- otherwise a rushed mess with annoying characters and dubious focus on the hunt of a little girl instead of the teeange virginal heroinne...not a good move- at all.
"The Curse of Michael Myers" is okay, messy yes, but watchable.
"H20" has a couple of really suspenseful moments, but doesn't manage to make the very most out of having Jamie Lee back, a bit too "Screm"-esque too for my liking.
The less said about "Resurrection" the better imho- horrible failure!