Okay, then let's see if we can come up with 16. I'll consider cross class skills as if you can use all of them at once instead of just five.

Bar 1(The abilities you'll probably use most often)

Fast Blade(Enmity 1)
Savage Blade(Enmity 2)
Riot Blade(MP Gain)
Rage of Halone(Enmity 3)
Circle of Skorn(AOE Off GCD Skill)
Spirits Within(Off GCD Skill; Silences)
Shield Lob(Start fights)
Shield Bash(Stun)
Shield Swipe(TP Saving)
Flash(AOE Hate)
Rampart(-20% damage)
Convalescence(+20% healing)
Fight or Flight(+30% damage)
Foresight(+20% Defense)
Bulwark(+60% block chance)
Sentinel(-40% damage)

Bar 2

Sword Oath(DPS Stance)
Shield Oath(Tank Stance; Don't need quick access to stances because they're permanently on until you die)
Awareness(Situational cooldown, immunity to critical hits)
Stoneskin(3 second cast time; situational because you'll often be interrupted during the cast)
Raise(Can't use in battle, but nice to have sometimes outside of it)
Fracture(DOT, won't be using constantly.)
Tempered Will(Situational; removes bind and heavy and prevents knockback/draw in)
Cover(Situational; absorbs physical damage for a party member)
Hallowed Ground(Situational; 10 seconds of invincibility from most attacks)
Cure(The last thing you want to be doing is casting cure on yourself. If that's ever necessary, you've already lost)
Protect(Your healer will already have it, but can be nice for soloing)
Skull Sunder(No point in ever having)
Mercy Stroke(Situational; only usable when an enemy is below 20% health)

And, I think that covers every skill a Paladin can currently use!