1 is more correct (not strictly so, but in terms of natural use of the language) because the term 'whether' is better fitted to the context because you're giving people a mutually exclusive 'choice' of loving or hating the subject. The term IF is better suited to other types of clauses that I wont explain fully here:) However, the use of IF is still acceptable and understandable! In terms of meaning, both sentences ultimately say the same thing, and the use of 'whether' doesn't necessarily mean to include all the possibilities in between loving and hating, it would actually mean one or the other in this case so it's quite restrictive and all inclusive (not ranging between).
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