I use both Aspen and newspaper, not together though. They both have their advantages, you can spot clean aspen but not newspaper, but newspaper is cheaper and messes on newspaper are easier to clean up, just ball up the newspaper and you're done, but it doesn't look as appealing as aspen. You can't go wrong with either.

For a new acquisition, I'd recommend newspaper to start, its easier to spot mites and treat mites than on aspen.