I'm preparing an online magazine, similar to the one compellingsciencefiction has (which, as its name implies, is based around hard science fiction)

There are already a couple writers interested in participating, however I'm wondering which theme should the magazine tackle.

Would you read stories where the "topic" is different each month (plague, outworldly invasion, dystopy, etc)? Or maybe the genre changes monthly (fantasy,science fiction, western)? Or would you prefer a magazine that focuses specifically on one genre only, say, fantasy?