Hm... I dunno, though to be fair, I think that my vote would have to lean towards Cleocatra, aka Ankha. I dunno, she has this air about her where she would ironically call everyone "Peasants".
I like Lucky's mummy design more, but Ankha also has a great design and I feel that she has a far better personality. If I absolutely had to choose, despite how much I love mummies, I'd have to give the vote to Ankha due to the previously mentioned reasons and because she can potentially end up giving you the throne so you don't need to waste bells purchasing one.
That said, since it's an option on the poll, I'm going with both and I do actually have both of them living in the same town.
As far as the question you posed is concerned, I'd say they would work in a time-themed town. Now that I see that mentioned, it's actually a pretty interesting and appealing idea for a town. I can see a lot of possibilities. Tucker could represent prehistoric creatures, Lucky & Ankha from Ancient Egypt, Julian and Drago from the early European folklore, Beardo from the 1800s/early 1900s, Ribbot representing the future. There are probably other good candidates for such a town that I'm not thinking of at the moment, but those were the ones that jumped out at me.
Don't really see how they'd fit in a Sun & Moon town unless it was less Pokemon Sun & Moon and more to do with the actual sun and moon, day and night sort of deal. If that were the case I could see Ankha representing the sun because of Ra, the Ancient Egyptian god of the Sun. Lucky doesn't really scream "moon" or really anything lunar, but he can kind of be related to the night since, if he's actually a mummy, he has technically died at some point. Death, darkness, and the moon in this case being in contrast to life, light, and the sun. All up to personal interpretation of course, that's just the way I'd look at it.
I would definitely choose Lucky over Ankha; I'm not a huge fan of snooty villagers, or cat villagers really so I guess I'm kind of biased lol but Lucky's design is so cute! I typically enjoy lazy villagers more than a lot of the other personalities as well, they're super laid back and nice, and dog villagers are adorable. As far as sun and moon goes I'm not sure who fits better, but Lucky is definitely my pick.