A solution to ranged vs melee: nuclear disarmament.

1 Minute Ago It's really not that complex an issue.

Step 1) marksmen have too long range. Reduce the autoattack range of every marksman by a decent amount (say, down to a standard range of 500 rather than 550, with champs adjusted from there) and then tweak the oddball ranged champs who would become imbalanced from that (ex, Annie, Thresh) as well as a few of the ranged toplaners. Then, adjust spells for range. The longest range spells like Ziggs bomb and ori command attack may need range reductions or mana cost increases.

Step 2) for the love of god fix the turret aggro when dealing with attacks at long range. Make it so if you hear the aggro noise for whatever reason, you are taking at least one turret shot. No more go in harass go out go in for ranged champs or throwing random abilities under turrets to harass for 20 minutes.

Step 3) now that range is mostly solved, let's look at melee. If a champ has mobility, tankiness and cc with no damage? They're fine. If a champ has huge mobility and damage with some cc but no tankiness? They're fine. If a champ has all four (IE Jax, Renekton, Irelia, Jarvan, Evelynn) they need adjusting so that their offerings are truly a "jack of all trades but master of none". This would be champ specific-say they removed Jax's ability to counter strike and leap strike at the same time to increase the Counterplay window to counter strike. Or they made it so Renekton's Dice resets on his using his stun rather than hitting an enemy with slice, so he can't slice-dice-stun. Maybe Jarvan's cc could ramp up to the closer the enemy is to Jarvan (Knockback is at a minimum at the end of his E+Q charge, slow is a minimum at max range, but increased when they start near Jarvan). Remember, with all of these, the size of the gap has significantly decreased, so there's reduced need for huge gapclosers.

And now you have decreased power to marksmen and long ranged mages, a viable niche for burst mages and assassins, a healthier lane phase and a separate role for true tanks and bruiser duelists.