From all the comparisons I have done, Colemak comes in after Dvorak as an optimum layout for typing code. So for programming, Dvorak seems to be better. But if you are not looking to do alot of coding on a Unix platform, I recommend Dvorak. If you want to use the normal shortcuts plus more, Colemak is your answer.

On the whole Dvorak seems to be better designed for normal english typing, while Colemak seems to better for standard computing.

To me, from personal experience, I can say that for anyone who never touchtyped before, dvorak is an excellent option. The layout is easy to learn and the hand alteration gives great accuracy. If the person doesn't use linux or unix, isn't a graphics professional and doesn't use keyboard shortcuts that much, dvorak to me is an awesome start.
Colemak to me, lends itself to the seasoned computer user who needs the shortcuts. Users like graghics pros need to use key combinations to speed up their work. Colemak makes shortcuts far more easier than probably the coders at Adobe would realize when they made them for QWERTY.
Of course extensive reamapping is required for the same with dvorak.

I'm still using the shortcuts at work so I'm still currently using Colemak. But to my hands, Dvorak felt far more comfortable.

Simply learning them isn't enough if they're on the other side of the keyboard. Some software allow for customization but one – you'd have to do it for every program, and two – you can't do it for some aspects of many programs. And also even if customized, the new shortcuts would be mostly meaningless, since they'd have to be made up by punctuation characters and vowels.

I wholeheartedly believe that using a software efficiently does require keyboard shortcuts. Does that mean that I think Dvorak isn't any good for anyone working on computer? Not necessarily but Colemak is certainly better in my eyes unless most of the work involves typing text. Then the shortcut factor wouldn't be as important and the layout choice would be dictated by the other factors.

According to Carpalx, Colemak is 13.9% better than Dvorak, but that's too objective.

Subjectively, both are good to the hands, though Dvorak makes the right hand to work much more than the left one. Colemak is more balanced.

QWAZXCVBHM remains the same in Colemak, so the switch to Colemak is easier.

I think the real benefits of one over the other are probably too miniscule to truly make a difference.  You'd probably be better off looking at other factors, like availability.  Dvorak has the slight edge here if you will be on other people's computers, but if you are primarily on your own and know that you won't have any trouble installing layouts on other machines you come across then you might not care.

I primarily run Linux on my own machines, so there's absolutely no problem there (both Dvorak and Colemak are well-supported in most free and open source operating systems without the need to install anything).  However, I took into account that I may need to be on a system that is not my own at some point or from time to time, so to avoid the trouble I chose Dvorak.  Even among Linux distributions and the BSDs, Colemak is not 100% guaranteed to be available; I know it is not in Finnix, and as far as I know it was refused by the OpenBSD guys (basically Theo, being an ass as usual).   Newer Apple Mac OS X releases apparently support Colemak as well.

If you can't decide based on platform availability (ie. an even split), then just type on both of them for a bit and note how they feel.  Decide based on that.  If you still can't decide after that, then damn it, just pick one! :P

But seriously, I don't think you can go wrong either way.  They're both miles ahead of QWERTY.

(@knightjp Regarding my pain, I was in agony with neck issues, that's when I decided to learn Dvorak in desperation.  I still have bad days, but I can't attribute it to the layout I use, more likely it's continued computer related stress.  Oh and I moved the mouse to the left a couple of years before picking up Dvorak.)

Considering at work I use my own system at work and it's running WinXP I had to request the IT dept to install Colemak for me. I use a Mac at home and it has Colemak preinstalled. At both places I've also changed the keycaps on the keyboards.
I'm also taking into consideration that my computer may be used by other users in the office on a very rare occasion. If that is the case, which of the two would you suggest if someone else was going to use your computer.

Left hand mousing on Colemak is rather useless. For one major thing for me, would be the fact that I could not use the keyboard shortcuts and the mouse at the same time. On the other hand, with Dvorak it would prove to be quite ergonomic. Considering that CTRL + Z/X/C/V & Ctrl+T, Ctrl+S would easily be as accessible on the right hand as they are on Colemak positions.

I'm not in the IT dept. So if I need something at work, I need to request the IT guys to install it. They are planning to give us new systems and sinc those are going to be Win7, that would mean that I will need to request Colemak to be installed. That way Dvorak has the advantage being that it comes installed. But like I said above, I would need to change to left handed mousing to make the shortcuts work effectively. Plus at work now I don't have the facility to change my capslock to backspace. At home on the Mac its a breeze to change and work on any layout you want. God I wish that they would give us Macs at work.

The one question I do have, on occasion if someone was to use my terminal at work, they would notice the change in the keycaps, depending on the layout I use. Would Colemak make it easier for them or Dvorak. Also I don't think that they will be that used to lefthand mousing if it was Dvorak.

Why have you stayed with Dvorak? You don't think that Colemak would help solve that pain?

It doesn't hurt to ask, with explanation why – it would improve your performance and all that. A simple portable executable file is most times not a problem to run (at least from what I've seen in different firms).

And why do you need to change the key caps? You can just leave the Qwerty ones, and whoever comes to use your computer can just switch the language (or stop the AHK file). And you touch type anyway...

Also if you learn to type Colemakd Dvorak, or whatever on a Qwerty layout it would be more beneficial, if you ask me. Having the Qwerty keys always makes it much easier to type on others' keyboards, and after a while you immediately know which letter is what – if you need to press only one letter with one finger :) If I had to type on Colemak arranged keyboard I'd be completely confused if I looked down, and I'm sure many would agree with me on this.

Considering that I'm going cold turkey on Colemak, would it be hardes to get used to the layout using a keyboard with keycaps on the QWERTY layout? I thinking it would.

Exactly what Tony said.

Some people even say it's more difficult to learn the layout if the key caps were on the right places because you are tempted to look every now and then. I don't know how true that is but most of us here have learnt Colemak on non-Colemak keyboards.