Married bertia is (among) the best. Plenty of other villainesses beats her handily before that, but when she lost the annoying plot-point of her having to intend to give up on the deredere relationship with the person she likes, she really did get up there among the best.
Though even before marriage she was probably the only reincarnated villainess that weren't in a yuri novel, with even a foot on the elite playing-field. Sure, plenty of others were better in various other aspects (ie. being an actual
realistic person), but enjoyment to read is where it matters