ErgoDox EZ vs Kinesis Advantage2

You can map any key to any position easily using a simple GUI, including making hardware key layers. And, since the firmware is open source, you can modify it to do anything you want. Many of the hardware components can also be altered/replaced by equivalent parts.

You can arrange each side of the keyboard to match your hand positions. Helps keep your body straight and improve your posture.

Because of its split design, the ErgoDox lets you optimize the positioning of its halves according to what's best for your body shape, even if you have broad shoulders and large hands.

The ErgoDox has an open design, so if you want to modify anything at all, you can fork the Github repository.

There are more keys which are easily accessible for touch typists than on common keyboards.

Unlike other keyboards, like the Lexmark M15 and Cherry G80-5000, where the only action performable by the thumbs is punching the spacebar, ErgoDox has extra keys placed near the spacebar, within thumb reach. This prevents the thumbs from being a bit redundant.

Almost all the keyboards have a small row offset (for example, on a standard QWERTY keyboard, the A key is not directly below the Q key. On the ErgoDox, this isn't the case: keys form straight columns. Together with the movability of the two parts you can stretch your fingers straight on, not slightly sidewards. This helps with touch typing, since you just need to stretch your fingers straight onward to reach the key above, rather than stretching it onwards and sideways.

Because of the nature of ErgoDox, within an open source community, there are advancements in firmware being made continuously.

With most programmable keyboards, you have to use their software in order to save and reuse your customizations. Using such keyboards on other systems "degrades" them to their default setting. Since with the ErgoDox the settings are saved directly on the keyboard, no matter the system where you're using it, your macros, tap dances and layers are always available.

The Ergodox doesn't allow you to reach over the centerline to hit T and H with a single finger, or whatever other bad habits you might have. The split design forces you to keep your hands in the right position.

The pre-assembled version offers an extensive 2-year warranty, provided you haven't taken it apart or physically broken it.

You can put the keyboards together, making it very easy to carry around.

Having multiple keys under the thumbs lets you keep the rest of your hands still, and helps prevent reaching. For example, the backspace key on a regular keyboard is way in the top right corner, while on the Kinesis keyboard it's under the left thumb. So, to hit the backspace button you just need to move your thumb while on regular keyboards you need to move your whole right hand and stretch your pinky to reach it.

This keyboard is sculpted to fit the curvature of your hand more naturally than regular flat boards. This helps reduce the risks of suffering repetitive strain injuries.

One of this keyboard's best features is that the keys are vertically aligned in straight columns, so that you're not constantly exercising the muscles to move your fingers slightly to the left or to the right. It makes a huge difference.

The large, raised palm rests provide comfort while typing.

Besides the option of easily changing between pre-programmed layouts of these 3 systems, extra OS-specific keycaps come with the keyboard.

This keyboard has several programmable options, like Macro recording, key remapping or keyboard layout (the keyboard can be changed from QWERTY to Dvorak with the touch of a button).

Because of its size, this keyboard stands firmly on the desk and doesn't suffer from unwanted movement during use.

The keyboard has the dvorak layout built in, so you can switch with a keypress.

This keyboard has numerous ergonomic advantages over a keyboard with a standard layout. Some of them are obvious and some are subtle, but they are synergistic and result in a typing experience that places far less stress on the hands. Learning a tweaked keyboard layout is a small price to pay to avoid RSI (repetitive strain injury).

On common keyboards, both thumbs rest over the spacebar, meaning they can knock against each other. On the Advantage 2 keyboard, only one thumb can press the keyboard, eliminating this problem.

This layout, because of its uniqueness, is perfect to learn touch typing. Even for those that were never able to learn it with common keyboards. It still requires practice to get proficient, of course.