The keychain is really EDC for everyone. When people, mainly my wife, asks me why I spend so much time and thought and money on "trinkets" and "gadgets" I carry, I usually respond (in my head) with this: everyone carries something with them every day, may as well be nice and useful stuff. To this end, when your analyzing what you carry and why, begin with your keychain.
In the modern world the keychain is almost universal. Even city folks that live in apartments or dorms with card passes and take public transportation everywhere have a few keys. Carrying around a wad of keys can be really annoying--they jangle, they take up space, the beat the shit out of other stuff in your pocket, and they weight a lot for their size. Thinking about what you carry on your keychain can help you organize and manage the rest of what you carry. With a well-thought out keychain your other items can work to supplement each other more effectively and hopefully you get rid of the janitor look. As a janitor in college I can tell you that even janitors hate the key wad.
The first place to look, before you get into all the fancy tools and custom prybars, is the keychain itself. Here is a good thread on keychain or key carry methods. If you can't find something in that list to suit you, well, grab some metal and a Dremel and get to work.
From where I stand, after literally years of tinkering, there one key carry method that bests them all--the coated aircraft cable. Here is a good representative model:
There are a couple of other configurations, ones with weird lugs on them to keep them closed, ones with latches instead of threaded connectors, but I have tried them all and this design is the best. There are uncoated versions too, from County Comm (a fun and weird place to browse around), but when they fray there are some pokey wires sticking out--not a good option for pocket dwelling (pockets being perilously close to the junk).
It is quick to open and close. It stays closed until you want it open. It does not add bulk (weighing well under half an ounce). It is widely available (I get mine at the key section of the local Ace Hardware). And it is amazingly cheap--$2.00.
This is not just opinion, though there is a bit of that. It is experience. I have had just about every system under the sun--the marine hardware, the split ring, the wallet carry...none beat the coated aircraft cable for all around performance.
There are some other options out there--much more complex options--and they have serious drawbacks in my opinion.
First there is Keyport. For about $80 on a basic set up, they will grind your keys (or copies) down to just the spine and then insert them into a box with sliders. The keys will slide out of the sleek looking box. The box can also hold a USB drive, which is a great idea. All of this requires you to send them keys and go to a local key store. It also means that wherever you use your keys you need to have some clearance, as the keys cannot readily come out of the little slider box. Finally, it is pricey. I like the idea, but I can't see it working. How often do you remove a key from your keychain? I do once every 4,000 miles when someone changes my oil (BTW: an oil change is now less than the cost of the oil from auto parts store...how the hell is that possible?). How often do you get a new key? And what do you with all the STUPID key fobs car manufacturers insist on producing? If you are carless, the Keyport makes a lot more sense. But if not, I think it is an $80 semi-solution.
Then there is this:
It was a mod that hit big on the internet blog circuit being featured at a favorite blog of mine: toolmonger.com It originated on EDCF (my home forum, I am rawls there after John Rawls). The idea is that through the use of a Dremel you mod your keys to fit into the tool slots on a Leatherman Micra or a rip off of the Micra. It is the favorite key carry method of brainsploded and is featured on his blog, everyday-carry.com (thanks for the link dude). I love the craftiness of the mod, but again the inability to remove keys or add them on the fly hurts this method in my opinion. If you are really settled in life and know you will not add or subtract keys, then this is an awesome way to go. There is, of course, a SAK version of this mod.
Finally, there is marine hardware route. There are million different steel, aluminum, and titanium parts out there that you can mod or repurpose to carry your keys. Berkeley Point is a great place to start. They have a wide selection of weird stuff and great measurements to allow you to do mock ups and avoid buying slightly to big things. Some of the options out there, like the Ti Snap Shackle
are awesome. But Holy Wallet Raider, Batman! that thing is $100. There are other cheaper alternatives at Berkeley Point, so browse around. Lowes and Home Depot have a pale imitation of BP's selection, but it is nice to see and feel something in person sometimes. In addition to cost, the weight of these items is a real draw back. Many are bulky. They may help you organize, but they will also help you walk on the bottom of the ocean should you and your keychain fall overboard.
I hope that is a good start on how to choose your method of key carrying. You have to choose something, so how about starting your EDC by pitching to stupid split ring and looking for something better and unusual. My mechanic loves my keychain, BTW. He comments on it every time he changes my oil for less than it costs to buy it.