Alterkation or K1?

What are the attributes of the coilover type suspensions that are appealing to you? Adjustability? Bigger selection of brake kits? Rack and pinion? Weight reduction?

I have an Alter-k-tion in a 70 'cuda. I have also amassed the parts for an all out torsion bar suspension for my Valiant.
After all the stuff I have bought for the Valiant I could have bought a QA1 or Alter-k-tion. I really wanted to optimize an OE suspension though. I have achieved laser crisp handling with the 'cuda and it's Alter-k and triangulated 4 link rear. Just wanted to do it old school this time.
I can attest to how well the stuff from Reilly Motorsports works. To match that with the OEM suspension I went all in on the Bergman Autocraft, Firm Feel, and Hotchkis parts. I also got an electronic power assisted steering unit. I have what I think is the best of the best parts you can get for a serious OE road race/ autox suspension. It's not cheap. I had the k-member hot tanked, sandblasted and welded up gussets and at the seems too. With the coilover suspensions you have to do a lot of stiffening too so think about that. Required is j-bars or the inner fender stiffening from US Cartool or XV since you remove the t-bars.
One of my favorite things about the coilover suspensions is the rack and pinion. To meet that satisfaction with the OE suspension I bought the EPAS unit. I also spent big on Doctor Diffs Viper brake kit. Those are two purchases that put the cost of the optimized OE suspension up there with the Alter-k-tion.
A good thing about the Alter-k-tion is you don't have to research and figure out what aftermarket parts for OEM suspensions work with each other. It really is a complete package other than your choice of brakes and the stiffening. The chassis stiffening is a wash because if you want to build a serious track car you are going to brace the car either way. Same thing with the brakes. You could spend thousands on Mopar spindle brakes if you wanted top of the line Baer. Premium brakes are going to be expensive either road you choose.
For me, the rack and pinion put the Alter-k-tion over an OE suspension. That is until EPAS came out and I'm really hoping it pays off.
A huge benefit to coilover suspensions is the cavernous space to fit headers. A torsion bar car is always going to suffer there.
Maybe the biggest benefit of the OE suspension is that you can continue to drive the car while upgrading to Hotchkis shock, Borgeson boxes, bigger torsion bars, SPC upper control arms,...... With the coilover suspensions you have to go all in with one shot.
Don't let a coilover guy tell you that the torsion bar stuff is antiquated. And don't let a torsion bar guy tell you OEM stuff is cheaper for the same level of performance. IMO, if you want an OEM suspension to perform as good as the coilover systems with a stiffened chassis you are going to spend the same amount.