Huh, I had kind-of expected the Kreacher match to be a landslide for Kreacher. Looking at the vote totals, apparently I need to provide supporting arguments o_O
(I suppose spoilers)
The initial premise for Kreacher is...interesting, if not entirely standout. Kind-of a reverse Dobby--a house elf loyal to dark wizards and forced to serve light wizards. I happen to find it a more entertaining premise, but that's a style thing (I'm more amused by snarky and underhanded insults than I am by blind adoration and praise). If the books ended at book 6 he'd well...he'd have a couple of good smart-ass one liners ("Master Malfoy moves with a nobility that befits his pure blood") but that's about it.
But then there's book 7. First of note, Kreacher is one of the few characters who gets significant character development. He doesn't behave the same way at the end of the series as he does at the start of the series. But where I feel Kreacher is actually pretty brilliant is the way in which this is done. Kreacher is not human and does not think like a human--and I really should emphasize just how hard it is to do non-human psychology; usually when I see authors attempt it, it just does not really work for me. In the case of Kreacher, however, it's quite well-done. Harry actually yells at Kreacher "I don't get it: Regulus was against Voldemort. We're against Voldemort. Why aren't you on our side?" and it's explained to Harry that elf brains just don't work like that. It's not until Harry says "we want to help you finish master Regulus' last task" that Kreacher's loyalties begin to change. Elf brains are focused on tasks and individuals rather than groups and political affiliations--even though their masters might train them about wizarding politics, and they might repeat what they hear, their minds actually operate on a different granularity most of the time.
The moment is also a pretty nice payoff to years of "Oh, is Hermione ranting about Elves again? Are these elf rants ever going to be relevant at all?"
All-in-all, it just feels like some pretty decent execution on something that's fairly hard to write (non-human psychology. Making an irrelevant story arc actually relevant).
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Cats land on their feet. Toast lands peanut butter side down. A cat with toast strapped to its back will hover above the ground in a state of quantum indecision