iPhone 5 or Samsung Galaxy S3?

This is a tough decision. The Samsung Galaxy S3 is a terrific phone. And so is the Apple iPhone 5. In fact, CNET's Brian Tong said it was impossible to go wrong with either smartphone. 

It's the battle you've been waiting for between the iPhone 5 and the Galaxy S3 before the Jelly Bean update.

But there are plenty of reasons to choose the Samsung Galaxy S3 instead of the iPhone 5. For example, the market research firm IHS iSuppli just published a study in which it said that the display on the Samsung Galaxy S3 is superior to the new iPhone 5's display. According to the report, The Galaxy S3's display, which is just 1.1 millimeters thick, offers the full color gamut of the National Television System Committee or NTSC standard. By comparison, the iPhone 5, which measures 1.5 millimeters thick, offers only 72 percent of the standard color gamut.
Some people say this doesn't necessarily mean that the screen is really any better. CNET's own Jessica Dolcourt did a round up of the best screens on the market and she ranks the Samsung Galaxy SIII at the bottom, while giving high marks to the iPhone 5. You may need to check out the displays for yourself to determine which one is best for you.
Keep in mind, Android phones are more configurable than iOS devices. And that's still the case when you look at the iPhone 5 compared to the Samsung Galaxy S3. This means you'll have a lot more flexibility in customizing the Samsung Galaxy SIII than you would the iPhone 5. Given that you are an IT guy, I imagine you aren't afraid to play around with your device. My guess is you won't have any trouble adapting to the Samsung Galaxy SIII. The Ice Cream Sandwich user interface is not that complicated to use. And the interface will only get better once it's upgraded to Android 4.1 Jelly Bean.
I also agree that it's very nice to be able to use any microUSB cable and charger with your smartphone. I've had a lot of devices pass through my home over the years, and it is nice when I don't have to hunt through my drawer to find just the right charger for each device. It also means that I can leave chargers in different places. I have one that I keep in my bedroom. Another I have in the living room, and a third one I leave at the office. This way, I'm never without a charger when the battery goes low.
I used to be able to do the same thing with my iPhone 3GS, since it used the same charger as my iPod. (Plus I had previously owned an iPhone 3G and kept that charger.) But the fact that Apple has changed the charging input in this version of the iPhone and the fact that it's not a standard microUSB is a pain in the butt. It doesn't seem like a big deal, but I think you're smart to consider this practical aspect when deciding which device to get, especially if you're already on the fence.