I'd use HeroForge. It's a free Excel spreadsheet for PC generation, but makes classed enemy creation a breeze. And you can print out stat blocks rather than a full sheet if you wish.
On the same hosting site is Monster Forge, with which you can advance monsters (adding HD, Feats, Special Abilities, etc.) and making them a bit tougher if needed. Again, there's a Statblock output rather than a full sheet.