Pittodrie aside (for matters of the heart rather than its beauty or atmosphere), I would go for Rijeka's old ground for aesthetic reasons (constructed on a rock face) and Real Zaragoza for atmospheric reasons in a tight old old fashioned stadium.
For money spent but retaining class and uniqueness then I would go for Luzern.
It's difficult though because football grounds can impress you for a variety of reasons. For example, I like Livvy because of the sight lines.
I think I would like Braga too but I've never been there