Many of the vets of the old forum will know that I'm solidly behind Chon Ji and Saju Jirugi as being some of the most application-rich patterns there are (I know that SJ isn't defined as a pattern in the system but ....).
They are the two most basic patterns in the system, and as such they don't have techniques that require skill, finesse or fine motor skills. The low block is especially good for adapting into clubbing strikes, the walking stance is great for disrupting the attacker's height, width and depth, the front punch (rear or lead) is simple and they're the two patterns that most people are going to practice the most during their time in Taekwondo. I love them.
I teach applications based on the level the student is at and below. For example, a green belt will practice apps from won-hyo downwards, a BB from the 3 BB patterns downwards.
I dont have a favorite, though I do favour certain applications contained within them over others when teaching groups.
Stuart
I Use Chil Sung Ee Ro Hyung for application.
I've amended the Hyung too. We got some serious stand up Grappling on the application as well as some really good throws and strikeing going on. I think when the new mats come I'll recoord it for Youtube and add the link here.
Thanks
My favorite form is Taegeuk il Jang. The reasons are
The last point also shows the difference betwen old style training (1 to 3 forms but deep study) to modern training (many forms and narrow study).