Um, I don't think I can help you with that, it seems kinda hard tbh, but I'll try!
If you did keep that town, you'd trade beau for Rosie, and possibly keep savannah or trade her for someone on your list. If you rerolled, then you'd have a chance at your dreamies (at least, the more expensive ones) but who knows how long that'll take. If it was me, I'd wait for at least 3 dreamies (or popular) villagers and then keep that and cycle. I don't know how long that'll take though, and if you have lots of time on your hands, then reroll. It all depends on whether you want to spend the extra time searching for those villagers, or are satisfied with these and start to cycle. That is just my opinion though, and it's really UP TO YOU.
I've had the same problem of wanting too many lazies (if only I could hoard them without the same dialogue) or too many dogs. I had to learn to let go and settle for variety to make the game more interesting. c: