I am not a Hal fan because he is one of those bland heroes created when DC needed non-controversial characters to help put the fallout from the Seduction of the Innocent book behind them. DC has added to the mythology of the Silver Age characters over the years and made some of them very interesting like Barry Allen. Hal has just stayed very bland and uninteresting in my mind. I do not hate the character. I just don’t find him compelling. He will always has a place in my collection because I am a fan of the concept of the GLC.
The animosity between Hal and John fans is probably caused by fans wanting what they believe is the best for their character. Hal fans want him to remain the main GL and always be considered the best GL. John fans want more exposure for him and for him to be recognized as the great character he is.