Win Rate Doesn't Mean Everything
Seriously, I see people picking champions who have high win rates saying, "Oh, this champion has a 56% win rate, they must be good!"
- loses
People pick Vayne (or some meta high-winrate pick) and say, "They must be good!" They check champion.gg and take a quick glance at the graphs, and say, "Yeah! Let's play this champion and win!"
- bronze 5
Come on, people. Look at the numbers. If a champion has, say, a 50% win rate, and only 2 people played the champion (highly unlikely, but it's an example), chances are, you're not gonna win those next few games. However, if a champion has a 48% win rate over the course of 20,000 players and games analyzed, that champion technically has a higher win rate than a champion with a 54% win rate with 8,000 players and games analyzed.
So, I'm looking at Yasuo's page on champion.gg, and he has a 46.92% win rate on the most frequent skill order, and a 53.91% win rate on the highest win rate skill order. This does not mean that you will do better if you max E first. If you check below the Most Frequent Skill Order graph, it will say "46.92% Win Rate | 8087 Games". If you check below the Highest Win % Skill Order graph, it will say "53.91% Win Rate | 1803 Games". The reason the Highest Win % Skill Order graph has, well, a higher win rate, is because less games were recorded, therefore the % is not as precise. You would honestly do better if you choose to choose the Most Frequent Skill Order graph, because you have a higher chance of getting a 46.92% win rate than a 53.91% win rate because the 46.92% win rate is more narrowed down.
TL;DR don't pick the Highest Win Rate over the Most Frequent, because the Highest Win Rate is less precise.
EDIT: Bonus information:
champion.gg samples games in a very strange way; they sample a bunch of games and say, "Oh, this is more frequent.", but then they sample a small amount of games (say, there's 100 games where people max W on Yasuo first, and for some odd reason that has a 60% win rate) and say it has a higher win rate. 60 out of 100 of those games were won where people maxed W on Yasuo first, but that 60 may not be proportional. If you, perhaps, ramp it up to 200 games measured, there's a chance that there will still be a 60% win rate (120 out of 200 games won), but it's not very likely. Typically the rate would lower, but can sometimes go higher.
If there are 10 games recorded where players max W on Yasuo first, and it has a 60% win rate, 6 out of 10 games were won. However, if you go ahead and decide 60% is an incredible number without checking the number of games recorded, you can lose, and then the win rate drops significantly; 6 out of 11 games are won, and now the win rate is 54%.
Basically, my point is, you should usually go with the most frequent because the results are way more narrowed down. Think of the number of games recorded as a "ticking" system. Each game recorded adds an update to the winrate graph. If 2 games are played, and one is lost, and the other is won, you have a 50% winrate, and now the very beginning of the graph is very spiked. However, over the course of 18,000 ticks, the graph begins to even out and becomes an almost perfectly straight line. Nerfs and buffs to the champion can change this number, so you'll get yet another spiked graph until it can even out. This is why, in most cases, when a champion is nerfed or buffed, their winrate can change drastically.
To add further to this point and really bring it all home, whenever you look at a Statistic, the more people are accounted for or the bigger the sample size is, the more reliable the statistic is.
