I won't debate here for long, so I'll make it short.
Kakuzu definitely has more experience than Luffy, but that doesn't really matter here. Since he's prone to violent outbursts, thus makes irrational decisions. On top of that he's too cautious when he sees a technique or ability he's never seen before and being too cautious is a fatal mistake, especially when facing Luffy.
Water manipulation, Kakuzu has that water heart, but we have never seen him actually using it (during his fight with Kakashi and the rest, and Ninja war). In other words, this heart is completely irrelevant, because A) we don't know what Jutsu it has, B) the range is unknown and C) why should we under assumption it's an offensive Jutsu in the first place?
Since we are primarily using the Character profiles and not "What ifs scenarios", it's irrelevant here.
Jiongu, it's basically like Tekkai, something that Luffy already dealt with (or is currently dealing with in this key).
Luffy's lightning resistance renders Kakuzu's lightning heart to nothing. Luffy could withstood 1 billion volt from Enel, so pretty much self-explanatory.
Zukokku may be a problem, but not something Luffy can't dodge. Overwhelming Luffy with sheer number, isn't really a good argument, since facing against multiple enemies at once is something he does on a daily basis.
Voting for Luffy.
