They are all cool and fun. Once you finish one, you immediately start another. So even if you don't like the one you made (I don't think this will happen), you can make another one.
There's all sorts of routes you go through, and you can repeat a branch to pursue other branches at your leisure. You're not gonna miss anything. You're not gonna be "stuck" with any single one unless you don't progress your study. You can display any Kao that you have earned even if you're still working on a different route to earn another. So it's not a static thing unless you've just started from the very first one as an absolute beginner on the site and don't have any other Kao.
Just as an example of what I mean, here are all the Kao I have so far, only one with the blue "Display" button is the active Kao I use for displaying on my profile, a level 25 one, from some arbitrary branch. The others are other Kao routes I've done, showing different Kao stages for each level milestone. They are all different ones in the end. It all comes down to which route you take. So if you keep studying, you get more like I have done and go through each cycle as you study:
