Collecting Foils

Hi everyone.

I recently started from scratch my MTG collection. Its purely based on the themes and art of the cards and the years I played (mostly Alara to Mirrodin, but I love Phyrexia set).

I read quite a lot of posts/articles that foils from some sets curl and its quite a job to put them right again or sometimes even they will come back to that u shape.

Question is: Which set/variant/block should I avoid completely when ordering online (since I cant see the card until the package arrives) to minimize risks ?

Thanks