Wow, surprising, and leaves me with a good bit to comment on. I've got three Evilutions (although David_Dweedle admitted bias) and just one Plutonia. One thing, though, I was a little unclear. I know Evilution earns more on music for having new tracks, however, I tend not to really consider "extras" like music (or sounds, though that doesn't apply here) in my assesments unless they are either particularily good or very annoying (the latter of which is usually a problem with sounds if anything).
I should also mention style. Since calling a wad better than another just for reasons of style is generally just a bias, I tend to pay more attention to the other less biased, more important elements that make maps, such as gameplay, actual design/architecture, originality, etc.
But yes, I should have seen that the way I worded the question, I was bound to get a bunch of "Evilution."'s for the new music that wad contains as well as the more varied style of its maps. So on second thought, the results so far don't surprise me as much as they did at first.
I can't say for sure if I would have said Evilution or still said Plutonia if I considered every single aspect equally, but I can say that my resounding vote for Plutonia was based on considering only the truely important (and less likely to be biased) elements. Although, actually, I don't really think the new tracks in Evilution are that much better than the stock Doom/Doom II tracks. But that's just my opinion, and they are somewhat a different style, so I can difinitely see why someone might actually think they are better. And I do agree that Evilution varies more in terms of style; I just, as I said, tend not to look at that as one of the more major points, since all it amounts to for the most part is personal preference, and it generally does not have that major an effect on enjoyability.
So all in all, I think I just need to make the question clearer if I want to truely get the analysis I'm hoping to gather:
Instead of just asking, "Which one is better?", I should ask, "Which one do you think is better in terms of gameplay, enjoyability, actual architecture/map design, and uniqueness?". Or at least, if you think one is better just because of something not as important like music or style, stating that that's the only reason would be preferred, so I at least know which one you'd think was better if you used my way of judgement. That way I'm not outright forcing you to use any particular method of judgement in your final answer, which I certainly don't have any intention of doing.
Alternatively, just as an idea, you could list each element (gameplay [which includes things like challenge/difficulty/fun], style, architecture/design, music, originality, and overall [as well as any other you can think of]) and say specifically which one you think is better in each category. I'm certainly not going to insist on anywhere near that much work, but I thought I'd mention it as an idea as it would be a good way of providing a clearer picture.
Of course, I do want to make clear that, ultimately, what you do is your choice. I certainly don't mean to be forcing for anything; I just want to give some suggestions and make sure I'm as clear as possible. That's all.