A mix of both is good! I love unpopular villagers like Croque, Pudge, and Rodney.. and of course I love popular villagers like Punchy, Dobie, and Ione.
I have some uncommon (sally, agent s, jeremiah, elmer, static), a few popular (marshal, diana, apollo petri?). I don't go for popular on purpose, only if I happen to like them
I usually prioritize my own personal preferences rather than focusing on whether a villager is popular or not.
Personally, I find myself more attached to villagers who aren’t overly saturated in popularity. When a friend gave me Marshal in New Leaf in 2013, I had no idea he was popular. If I had known at the time, it most likely would have influenced my perception of him and how others viewed him.
For example, villagers like Raymond - his popularity, especially when New Horizons was first released was overwhelming. When series 5 of the amiibo cards were released, I was selling and trading my duplicate amiibo cards on a local marketplace, and I had a spare Raymond. I was bombarded with offers of up to $50 for that single card alone. Experiences like that leave a lasting impression and affect how one perceives such a villager.
Hmm the popularity of a villager doesn't really hold much weight for me, but looking at the villagers I like I think it's a pretty even mix of both, Maybe leaning a bit towards the popular side?
I like a combination of popular and uncommon villagers. I pick just whatever I like regardless of popularity. My final roster each game depends on a variety of factors including sometimes what color scheme or vibe I want to achieve. I enjoy many villagers so picking just 10 is a challenge.
How popular or unpopular a villager is doesn't really affect my opinion of them at all. I'd say there's probably an even mix of popular and less popular villagers among my favorites