New tires for our '08 & '11 Yaris...P4 vs Defender?

[PlowTown Missile]

We have owned both cars since brand new and put at least 3k miles a month on them. They are our commuter cars but also do our long distances trips in them.

Her 2011 5door hatch needs new tires to replace the factory ones at 60k miles. Has averaged 37-39mpg since new.

My 2008 4door sedan needs new tires at 160k miles. I replaced the factory ones at 60k miles with Pirelli P4's and have 100k miles on them now. They actually still have decent tread left but they've been vibrating continually worse the last 30k miles and are cracking where the tread meets the sidewall. When the P4s were put on new, the car had a terrible vibration. They said it needed an alignment which was then done. Vibration was still there and it turned out to be a bad passenger front tire. They put another new one on and it cured 90% of the vibration. I'm pretty sure the passenger rear has been bad since new also so I never rotated my Pirelli P4s. That passenger rear has wore feathered since new even though a 4 wheel alignment was done when they were all pu t on. I'm also going to be having the dealer replace the original brakes on this car at the same time since it needs them. I'm still averaging 39-42mpg depending on how much I use my remote start to warm up/cool off this car.

I'm planning on keeping both cars til at least 250k miles (the sedan paid for itself a long time ago) so I've narrowed it down to these two tires. I'm happy with the way the P4s have performed except for the vibrations they've had (its 100% sure the tires are the vibration cause). I've also loved the Michelins on our RX350 and our Tundra so I'm torn between ordering another set of Pirelli P4s or the Michelin Defenders. Anyone have any experience with the Defenders that would make me feel they are worth the extra $$$?
Btw, I won't consider any other model tires but these two and both cars will be getting 4 wheel alignments immediately after the new tires go on.