@Ghostcrawler, I have an idea to make melee interaction more interesting

Every champion should have a toggle skill innately, that allows them to partially block autos with autos. This is an increase in complexity certainly, but bear with me and continue reading to see how this would improve league of legends. Generally you subtract your attack damage from the damage of the incoming auto attack, and note that you cannot critically block, and you cannot reduce the damage below 0 of course.

So you expend an auto attack to partially block an auto attack. Slice a bullet out of the sky. Snipe a rocket in midair. Parry a sword with an axe. The more attack damage you have, the more damage you block.

The toggle should have about a 3 second cooldown, so picking a defensive stance is an actual tactical investment that could backfire if you opponents act on the fact that you can't damage anyone with an auto attack for at least 3 seconds. In general, with critical strike chance or if the attackers attack damage or attack speed exceeds the attack damage or attack speed of the defender, the defender cannot mitigate all the damage from the attacker, so stalemates between auto attackers will not occur.

While toggled on your champion will automatically stop moving to parry an incoming auto attack. The number of times you can block per second is directly related to how much attack speed you have.

There may be items that allow you to spec into block, so that you can block far more attacks per second from multiple sources, but still no more frequently against a single attack source.

Doran's shield could be an item that specifically enhances the amount of damage you can block on each auto, as if you had 40 more attack damage for example.

Except perhaps for specific champions or specific actives, melee can block melee, ranged can block ranged, and melee can block ranged.

Tanks will generally survive by being very durable and not specifically building heavy into block, and are able to simultaneously auto attack or use abilities and be durable against any form of damage auto attack or otherwise. Fighters and brusiers in this system would differentiate themselves from tanks by generally having their durability and offensive capability be mutually exclusive-- either they can block damage (auto attacks) directed at them or attack, but not both simultaneously, and that modality would represent both a vulnerability and the ability to adapt to changing circumstances.