sorry this is long. disclaimer: this is all obviously my opinion, and i'd appreciate if people didn't call me names for it or act passive-aggressive in response to stuff i've said. you're welcome to disagree and/or prefer NH, that's your opinion, and i respect that so please respect mine.
NL hands down. i played one copy of that game everyday for 7 years starting from its release date, and a second copy for 6 of those same years. i still play both now, albeit every other day due to time constraints. i actually played both of them (individually) more than i played NH yesterday. for me, NL just has more to do and staggeringly more charm. i've never been fond of the decorating aspect of AC, and NL didn't force it in my face anywhere near as much as NH does. i wasn't one of those people who obsessively reset my town to get the ideal rock placements and perfect town hall locations etc. (have no issue with people who did, just saying i didn't.) i just picked a map i liked and worked with it, and i have two beautiful towns to show for that work. which isn't to say i wouldn't have taken movable rocks or the option to choose where villagers moved in, but c'est la vie. you can't control everything in life and NL reflected that. it is, after all, a life sim.
i love having all the NPCs around. i love brewster and his cafe and the part-time job, and how you could unlock special items by playing that mini-game. i love tortimer's island and playing the island tours, even if i do it alone. (i played the firefly tour a few times yesterday and god do i desperately wish those mini-games were in NH. yeah, yeah, "if you miss 'em, just go play NL", but i want to see them in NH's beautiful graphics with the dynamic lighting etc. sue me.) i miss all the things you could unlock, especially re: how main street would grow/transform as you progressed with the game. i really felt like i was contributing to my town and helping it become a better place. was the game without its flaws? no, of course not, but it's less flawed in my eyes than NH still is.
and is that to say i hate NH? no, of course not. i don't even dislike it overall, i'm just very disappointed in it. it's not necessarily a bad game, and its graphics are definitely a step up from NL's, but graphics aren't everything, and it's lacking a lot of the charm and character that all the previous AC titles have had for me. would i still recommend it? sure, but not at its launch price, and i'd definitely recommend NL over it without question.