this is a good question but a hard one! I think what's so cool about neocities is that there is no "one" way to run or design a website, so only showing them ONE would be reductive haha... but I guess I would probably pick one of the earliest ones that I saw on here, dokodemo (especially w the old layout), because the homepage is such a culture shock for someone Just coming off of Twitter or another site like that.
the boringly obvious answer is A.N. Lucas' web lounge. Most obvious and accurate to explain to someone what it is and the prevailing site culture. if it was someone whose tastes were similar to mine, though, and I wanted them to stick around? probably you or bikobatanari or bogleech, to present it as more of a hosting platform to put cool work in ANY format that appeals to your personal style
(vs just a place for the old web ~aesthetic~. AN Lucas describes the overall vibe best; you three demonstrate what I personally feel is the ideal usage: simple, clear, endlessly customizable presentation of creative content.)
I think I would also have to say A.N. Lucas as their website is not TOO big to new people to overwhelm them, but not too small to make them disappointed, plus I feel like it gets the V I B E S of the whole host down quite well
it wont have the next / prev page thing though because that thing always breaks
omga i like pokey!!