RE : So which gen of kpop would be considered the most iconic, impactful, legendary in few years down the line

Third gen (but maybe I'm biased because all the third gen groups were the very first ones I was introduced to). What other gen has BTS? BLACKPINK? Exo? Twice? You get the idea. So many groups pushed so many boundaries and broke world records.

Before BTS, it was probably unfathomable that any K-Pop group would ever go to the Grammy's. Before BLACKPINK, people probably didn't know that a girl group would get so popular and be known all over the world. They, along with countless other groups, completely changed the game and helped introduce the world to K-Pop. While other groups were all very famous in their own right, there was, and still is, just something special about those two that no other generation has.

for me it is 2nd gen, cause it really was my childhood

Still second gen imo, not only because it's the era I discovered K pop, but for the groups and songs in that period that have stood the test of time and have influenced current groups.

3rd gen because of BTS.

2nd - early 3rd for me

probably 3rd

2n gen for me