Which one is best depends on what you do. Personally, I have never seen the MacBook Pro as a 'gaming' laptop. Some people I am sure feel the other way. I mean, I can't really say there are many 'gaming' laptops at all given gaming with a desktop is so much more cost efficient and laptops lack many of the features that gamers seem to like.
Additionally, you have to keep in mind we are biased towards Macs as we are here.
Personally, I would not even consider the Razer although I like a lot of their products. Why? Mainly because it doesn't have OS X. And many other users here will say the same. While I am not trying to take anything away from Windows 7, OS X does the things I want it to in a fashion that I want it to at a speed I want it to that Windows simply doesn't. And so for what I do, OS X in itself is what justifies the MBP as the Mac OS makes my work more productive. The features that OS X offers, the free software, the ability to make software, the overall stability, and the integration with the iPhone are all big things to me. However, you may not care about that which is why it is hard to say which is best.
Other things that the MBP will have over the Razer? The trackpad is a big one. Considering that you will use the trackpad most of the time you use the computer, this advantage should not be taken lightly. Use the MBP trackpad for a year or so and then try a standard trackpad and you simply won't want to do it.
Is the Razer durable? I imagine so as most of their stuff I own has held up and support has been great. However, I can vouch first hand with the MBP. It holds up to daily, heavy, mobile usage very well. The battery does well, the screen quality is great, and the CPU has saved me hours of number crunching waits. I purchased mine a bit over a year ago. The CPU in mine is still one of the faster CPUs out there as far as laptops go as the quad core Sandy Bridges are fast like a bat out of hell. Obviously, the 2012 will be faster, but it is going to be a smaller step that looks more at efficiency. I've read everything from a proposed 5% to 30% performance increase so who knows what it actually will be when it comes out.
I just noticed the Razer has a dual core in it and not a quad...especially at that price it kind of surprised me. That dual core CPU appears to be the same one used in the MBP 13. Depending on what you want to do, that in itself could be a deciding factor given the 15 and 17 inch MBPs are now quad cores only.