Let's look at Lee Sin...
Free Resource sustain/ Attack speed
True sight / dash / % of health missing
Shield / Shield on teammate/ Dash / Health sustain
Aoe True Sight / AoE Slow
Multi-target damage / multi-target knock up / single target knock back.
14 goodies of utility before damage ratios.
Now we look at J4.
Current health % with a Cooldown
Armor shred / Dash ON COMBO
AOE slow / Shield
Self armor / Self Attack speed / Aura attack speed
Dash / Walling in that is easily escapable
9 goodies of utility before damage ratios. Mind you, Jarvan's passive has a cooldown on his target, he's gated by mana where Lee Sin has energy AND ENERGY REGEN, Jarvan's kit is an all-in kit, where as Lee Sin can go in and get out with ease.
So here's where it stands. Jarvan is extremely easy to kill compared to Lee Sin. Jarvan doesn't have sustain freely like Lee Sin. Now let's put in Damage Ratio's.
Lee Sin!
Q: Level 1: 100 + 180% bonus AD + 8% of missing Health. Level 5: 340 + 180% bonus AD + 8% of missing health
W: No damage ratio's, however, notable life steal here.
E: Level 1: 60 + 100% bonus AD, Level 5: 200 + 100% bonus AD
R: Level 1: (200 + 200% bonus AD)(Targets hit). Level 3: (600 + 200% bonus AD)(Targets hit)
Level 18 Ability burst on ONE target: 1140 + 480% bonus AD + 8% of missing health
Jarvan!
Q: Level 1: 70 + 120% bonus AD. Level 5: 250 + 120% bonus AD
W: No Damage Ratio
E: Level 1: 60 + 80% AP. Level 5: 240 + 80% AP
R: Level 1: 200 + 150% bonus AD. Level 3: 450 + 150% bonus AD
Level 18 ability burst on ONE target: 890 + 270% bonus AD + 80% AP
Clearly it is easy to see that Jarvan is beat by Lee Sin damage wise and utility wise even still. Not even the random 80% AP ratio Jarvan has can help him against a Lee Sin of equal skill level.
**However. Despite the obvious superiority in SOLO FIGHTING that Lee Sin has, Jarvan is better at team fighting because of his kit. Lee Sin's kit can help his team, but not to the level Jarvan can do. Lee Sin is good at picking a fight, trying to be alone with a target. Jarvan is good at engaging the enemy team with his own.
The two champs are strange to compare, because they are not designed for the same purpose.**