Well, apparently they do slightly attract the crop faries; also the fairy rose honey is a nice price, and there is a recipe (in late game) which uses them.
Fairy roses, though I pick and replant when they come up in the colours I don't like as much (Mostly the pinkish one), and pumpkins, and some sunflowers because if I ever pick them by accident the seeds are Right There (also, they seem to work well as gifts).
Pumpkins fit the Fall Vibe. Plus Abigail loves them. You can get a lot of gold from them plain, through Preserve Jars or Kegs (though of course Preserve Jars and Kegs can give you a lot more gold, it's still a solid crop to sell raw).
Sunflowers and Fairy Rose. Their honey sells for a lot, Sunflowers are loved by Haley. Fairy Rose are loved by Evelyn and Jas, they're easy loved gifts to give them. Sunflowers are a double season crop and can potentially give you extra seeds, which is nice.
People tend to buy a ton of cranberries for the harvest (I'll buy a decent amount of cranberries), but I end up buying a ton of Pumpkins.