One of the best sets of BBC Scifi ever was Quatermass, possibly the best ever.
And that had the tiniest fx budget ever, but they were proper scary.
Similarly Doomwatch if you ignored the rubber rats and papier mache chickens, is easily scarier and darker than the X files.
If only we could recapture that dark sensibility with some modern CGI.
We'd ruddy rule the world of TV scifi.
Ever seems to be my word for today.