Master Yi ghost vs flash, crit vs on hit.

A friend and I got into a fight after he flamed me for taking flash every game instead of ghost. Some games ghost could work, but flash is almost always better from my past experiences. Ghost isn't going to help me dodge a Malphite flash R, and it's tricky to alpha strike it since he can still hit you after.

The pros of Ghost.

1. Ghost has a lower cool down than flash.
2. It helps you chase when you use highlander since you can't be slowed.
3. You might be able to use it to escape when flash wouldn't help.

The cons of Ghost.

1. High cc teams will lock you down as soon as a single cc ability hits. Have fun dodging it all without flash.
2. Nearly useless when your ult is on cool down if the enemy team can slow you. Bork, and Yoummu's help with this.
3. Takes longer to get you where you need to go at first since you have to accelerate.

The pros of Flash.

1. Can flash over a wall.
2. Can use flash to dodge cc at critical moments in a team fight.
3. Can sometimes use it to escape where ghost would not help. Such as when your Ultimate is on cool down, and you can be slowed.

The cons of Flash

1. It's not as good for chasing as ghost is in a team fight, if the enemy team doesn't have any cc you have to dodge.
2. It has a far higher Cool down than Ghost does.
3. You can fail a flash over a wall, making it useless.

So do I not know enough about Master Yi's pros, and cons to just play with what I want? I'd like to point out my friend thinks Yi is super ez, and should stomp 100% of the time, but he is completely skill based, unless you get lucky alpha strike spamming.

I would also like build advice, I've been going Blood Razor, wits end, and black cleaver vs Rammus or any other thornmail tanks.

Rammus is especially dangerous, and I sometimes get a quick qss just to deal with his taunt. That way I can run away from Rammus, and focus someone else, and then come back to him when his R, and bonus damage reflect has worn off.

My friend says crit Yi is better, but in my experience crit Yi is sub par, and only shines when the enemy team can't dish out enough damage, or has very little cc.

Otherwise a tankier on hit build with frozen mallet, or black cleaver just seems better. I do more damage to champs with crit, but I also die a lot more often. Damage does not win games by itself. One wrong alpha strike in a team fight can screw you over if you are squishy, and I've lost games I would have won if I had been tankier. I've also lost some games where if I had went crit I would have probably won. I think it comes down to the team comps, and how well your teammates are doing.

For example, I had a jhin do 1.2k damage to champions in a 35 minute game. I went tanky on hit Yi, and couldn't carry, even when I 1v5 and kill three people in a teamfight. My team would still lose 2v4 after I died.

Watching the map carefully while you afk jungle camps can give you an insane advantage before you build too far into any one build with Yi, but I've also died afking a camp when I get blitzed by someone like Khazix, or Shaco, and they always show up when you least expect it, like at Krugs you think you were safe, but they just hop the wall.

In my honest opinion, on hit Yi is better than crit, if at least some of your teammates are competent, but there have been games where I wished I had more damage to try and solo carry people who were too afraid to fight back. Surviving longer in a team fight, and doing less damage isn't as good if you have to 1v5 every fight, and it is then that I think crit Yi with phantom dancer, IE, Guardian angel, boots, Spear of Shojin, and another item can shine.

Any experienced Yi mains that can give a new Yi main some advice? I've probably done less than fifty games as Master Yi, so I am far from experienced.