well i think that all the last battle need to be remembered as the best fighting scene of the series, the hogwarts siege its really awesome, all the death eaters trying to penetrate the castle defences and all the characters that have opposed to Lord Voldemort are joined together in one last battle, i believe that this part is unique , each time i read it i just cant stop !

i picked Molly Weasley vs Bellatrix Lestrange in the 7th book, just because i love the line, "not my daughter, you b****!"
it still makes me crack up, and plus, i hated bellatrix, and i was happy to see her go

THe fight scene between Molly and Bellatrix (the woman I love to hate!) was really a good one. It sort of made you want to jump up and yell YES!! I was glad Molly got that chance because she had sjpent so much of her time, sewing, cooking and taking care of everyone, it was good to see her in action.

My top three out of the options provided:

1. Harry vs. Lord Voldemort in the graveyard fourth year
2. Dumbledore vs. Lord Voldemort Ministry of Magic fifth year
3. Harry vs. Lord Voldemort Hogwarts Grounds/Forbidden Forest 7th year

Dumbledore versus Voldemort (Ministry of Magic, 5th year).
I like this particular fight scene the most because Dumbledore and Voldemort are the most powerful wizards, kind of Good versus Evil. Another thing is they knew each other for so long and they were fighting indirectly, it was about time to face one another.