Linux (Ubuntu) vs Windows 8 vs OS X
iOS vs Android vs Windows Mobile vs Whatever …
I’m not a “frontend developer.” That’s not my job. I’m a “backend” developer” and I only code PHP and MySQL on OS X. <-- Move away from this mentality and be more accepting of other technologies. Investors and businessmen don't care so much what's under the hood, and neither should you.
Don't limit yourself to a single OS or platform. Dabble in open source and use Linux*, OS X and Windows. Learn WordPress, Joomla, Drupal and Magento. Learn Django, Rails, Symfony and Ruby, Python and PHP. If you're wondering where to start, it's not the tools that matter, but how you use them. In IT, you'll always find a layer of abstraction above where you are right now. There's always a right tool for the job. Taking a top down approach, see the goal and work backwards on how to achieve it. It's true that if you know one programming language, you know them all, and even if you aren't as efficient with one language compared to another, those are "problems" that get streamlined early on.
Don't tie yourself down to an OS. Use whatever works for you. I don't have a "main" workstation. I have a Macbook Pro when I'm on the go and usually at home. I have Ubuntu and Windows on a desktop and Android on my phone. I am a developer. An engineer. I can code for all of these platforms and there's no reason to coerce yourself into one niche.
Zoom out and take note of the technologies and skills you've accumulated under your belt. These are all labels (i.e., a “wordpress developer” is or at least should be a PHP developer) Yes there are bad programmers and good programmers, but the difference isn’t in the code anymore. Working in IT means always being able to adapt to changes in trends. Make your work your sandbox. Don’t bullshit anyone, but don’t deny what you’re capable of either. Create.
See yourself as a problem solver and tackle challenges accordingly. Use your developer skillset to keep the wheels in motion. What makes programming worthwhile? Why reinvent the wheel when you can move the damn thing forward a millimeter or two?