In the 90’s and early 2000’s Happ used to order buttons and Joysticks from iL and then sold them as their own brand. They then copied the molds and joystick sometime in the mid 2000’s and had manufactured their knockoffs with a little bit of quality drop. Then a few years ago, happ went from cherry microswitches to e-switches. Anecdotally i’ve heard the e-switches are of lower quality but have never tested this myself.
In short, spend the extra money on iL parts. I heard that the diagonals on the new happ competitions are harder to hit than on an authentic iL joystick. Buttons I suppose are the same aside from the switches.