I will keep this post short and relevant just to end this debate once and for all. So - is there any skill difference between EUNE & EUW?

I will talk from my own experience (5 seasons on EUNE, 3 seasons on EUW). My opinions are also influenced in a major way in a point of view of other players who are high elo (Master +).

There is a difference. But not as huge as some people are implying when it comes to lower tiers (no, you can't be gold EUW and diamond EUNE). I am currently diamond 3 player on EUW and was able to peak Master on EUNE relatively easily in this season, so I must admit that west is definitely a lot harder in mid diamond.

Yes, players in mid diamond are definitely better on EUW than on EUNE, mainly when I think of the macro play. EUNE really lacks macro play and also mechanics are slightly worse on EUNE as well (I'm armless support though, so I don't need to care too much).

I used to smurf in lower elo (like gold) on both servers and it seems to me almost the same, maybe some very slight differences, but I would go as far as saying that difference is maybe one max two tiers.

When it comes to mid diamond I can already see a huge gap between EUNE & EUW, not to talk about Master (mainly higher Master, not people who played 2000 games to get there to drop next day) and Challenger players. Population density is higher on EUW and also all pro players play exclusively on EUW for a reason. I would estimate that people who are mid Master on EUW with solid win ratio can get easily top 10 challenger on EUNE, even top 1 if they want to if we want to demonstrate the huge difference in skill in the highest tier.

So in the end - if you want to go pro or to get really better, focus on playing on EUW, because EUNE is the server where you can chill and have fun, but it's nowhere as competitive as EUW (and nowhere as toxic from my experience).

I'm adding my challenger screenshot from s7 EUNE to brag (JK, I play for fun, but it was cool to get challenger anyways) ;)