Zilean's passive or kit could use a buff

I've just hit Zilean to level 5 today, and as someone who plays him a lot, I really want just 1 buff.

There are so many ideas for a better passive:

Bonus mana regen or health regen Zilean gives 10EXP every 5 seconds. Every level up, it grows by +2. Up to 44EXP to those around Zilean every 5 seconds. Make W his new passive and change the W to something else. (Down bellow is the change.) Passive now allows you to recast a ability a second time automatically. (E will not cost anything for a second cast.) Zilean converts every 10 AP into +1 AD for himself and ally champions. Range is 900. And more.

Buff the Q. Now that its a skill shot, can he not get some compensation. It is his only damage ability, and it costs a lot.

Raise the stun from 1.1/1.2/1.3/1.4/1.5 to 1.2/1.4/1.6/1.8/2 seconds.

The W is/was suppose to cost nothing on the PBE. Although it can now not be cast when Q or E are up, it still just sits there.

Make it cost nothing. Allow it to rewind abilities by 1/2/3/4/5 seconds to nearby allied champions. New W Heals ally over time. Cost is 80/90/100/110/120 mana. Cool down is 18/16/14/12/10 seconds. Zilean speeds up time to heal himself or an ally for 100/125/150/175/200 (+50% AP) over the next 4 seconds. On recast, it instead costs 10/20/30/40/50 mana. Second cast on the same ally revives their mana by 10% over the next 4 seconds. On someone else, it replenishes their HP by 6/7/8/9/10% (+[1% of every 100 AP]%) over 4 seconds; this one also happens to manillas champions.

The E is very strong, but...

Make the E last 3 seconds for each cast, to get a total of 6 seconds. Second casts on the same champion allow them 25% bonus AS or on enemies, -25% AS for 2.5 seconds.

The R is what makes Zilean a true support. It itself could use a buff.

Make the R cost 100 mana. Raise the AP ratio to 300%.

Right now, even Bard and Soraka beat out Zilean in usefulness since they have more in their kits.