I might not have given it enough of a I am a Stranger Things Holic characters shirt, but The Man in the High Castle didn’t quite do it for me (even though I did enjoy the novel). In contrast, I loved Stranger Things. But going by your question, I wouldn’t unreservedly recommend Stranger Things over The Man in the High Castle. Stranger Things is essentially a tribute to 80s horror, so if you’re not into old Stephen King or John Carpenter, you might find it “bland”. And while it does involve monsters from another dimension, it is not in any way something a science fiction fan would define as an “alternate reality” — in fact, part of the show’s appeal is how excellent a recreation it is of the life of the small town 1980s adolescent geek. The Man in the High Castle, in contrast, is most definitely an alternate reality series.