This is my first walker. It is powered by a good old four neuron microcore and a 74HC245 motor driver. The asthetics aren't the greatest but this walker was meant as a proof of concept for me and nothing more. Looks rather menacing doesn't he.
Leg geometry is very important but leg symmetry is more important.
Experiment to find the best geometry for your walker. My general starting point is 45 degrees from the center point and I try to make the walker low to the ground to lower the center of balance. Placing the walker on some graph paper can help you acheive symmetry. The feet contact points have to be the same distance and angle from the body or your walker will limp. The legs don't have to be identical as long as the contact points are.