The original, then III and Rob Zombie's Halloween 2. I don't stan for the rest. The original sequel has a great atmosphere and location but the acting is putrid and Laurie does NOTHING until the end. 4 is good but overrated. 5 is an abomination. 6 is a fun gory slasher but nothing more (the producer's cut is much better). H20 has some fantastic scenes but it is a mess. Resurrection has some good scenes as well but it never happened. The remake is AMAZING until Michael breaks out of the asylum and then it all falls apart.
Halloween 2 because of the part chasing her around the hospital has always been a part of my nightmares. *types this while lying in a hospital bed glancing up the door ever so often*