Agreed that what you think is the most important. You won't know how "decent" they are until you spend time with them. A bunch of my dreamies in my town I would have never picked, but since they showed up and I spent time with them, I started to love them. Other villagers, I didn't bond with even though they were popular, I let them go.
If you're asking about who is popular so you could trade them off, check out the
Villager Trading Plaza to see who people are trading. Also there's a list of how the villagers are categorized by popularity IN GENERAL, so not accounting for individual's tastes, and you can find that
here.
I've had and loved Bruce personally, but he's not very popular.
Marshal is the most popular as others have stated. I love him, he was a dreamie, and I find him ADORABLE. But if you don't, you can make tons of bells or trade him for ANYONE you want practically.
The octupuses are popular too.
Rosie is super cute, pretty popular, and again, I think lots of people want her.
I really suggest that you spend a little time with each of them first. You might end up loving them for different reasons other than if they are popular or not.