As for notably overhyped vodkas, Grey Goose holds a very special role in defining overpriced mediocrity.
It used to be one of my favorites before I discovered potatoes in 2010. Ten years ago, it was very obviously more refined than its competitors and you pay a premium for that. But it started slipping in quality, becoming harsher and less subtle. Same thing happened to Ketel One long before that, except it became ever more watery.
I picked up Vikingfjord and Monopolowa today and just had a quick taste so this is only a first impression:
Vikingfjord doesn't offend much. It keeps things pretty simple without being too bland, but there's a just a little too much bite to drink it neat. I expect it to be quite nice chilled however. It lacks oiliness relative to most potatoes: a potato trying to be a wheat?
Monopolowa is moderately oily, less so than B&B. It's quite smooth but fairly sweet and fruity, more than Tito's (which I dislike for that reason) but the oil restores some balance. I kind of enjoyed adding it to B&B in 1:3 to add a touch of smoothness. Vodka modding!