I can only really comment on the mini14 since that is the only rifle I have. (I'm relatively new to shooting). I have a stainless-ranch model with the wood stock. The only modification I have done is to replace the flimsy flip-up rear-sight with an M1-carbine milled rear sight.
I have fired a friend's AR and I have only looked at the SU-16 in a gunshop. I have no experience with the m96.
Personally I really like the mini14 for the following reasons:
Its pretty rugged and simple. It field strips very easily and does not have too many small parts that could be easy to lose. The hardest part to get really clean is the backside of the gas-block. You do need at least 1 tool to pry the trigger guard open. With the wood stock, the rifle is a solid 7 lbs or so, and feels like you could really whack someone with it if you had to.
For me, it has been very reliable. It went through the 4-day rifle class at Frontsight without a hick-up (that was when it was pretty much brand new with only about 150 rnds through it). It happened to be pretty windy that weekend with lots of blowing dust & such.
I like the fact that its an "open-receiver" design which makes it very easy to diagnose and clear any malfunctions that might occur.
I have been lucky so far and have not had a magazine that it does not feed reliably from. The only issue I have is when using frangile ammo (which has a flat nose instead of a pointed nose). Occasionally, the flat nose of the frangible round will lodge against the face of the chamber instead of feeding properly. I have not had any issues with std. FMJ rounds. For CA, I have found the promag 10 round magazines to be very reliable so far.
As far as optics, if you are going to put a traditional scope on it, then go with the ranch model. Its recevier has ring mounts machined into it and it comes with 1" ruger rings. There are also lots of options for other style optics in the scout or traditional configuration. You will have to buy some sort of weaver-style rail adapter though. Ultimak makes a very nice forward scout mount that replaces the entier upper handguard.
Since I am a relatively new shooter and bought the rifle primarily for plinking/home-defense/urban shtf it is accurate enough for me. The mini can be made pretty accurate for not too much $$ if you're willing to put a little time and effort into it. Go to
www.perfectunion.com They have a very active mini forum and discuss at length what they have done to accurize their rifles. The general consensus is that a muzzle brake/flash hider and a good bedding job will significantly improve a mini's accuracy. The other thing is the mini's front sight is big (which makes it durable & fast) but really hamper's accuracy at distance (though it might be me or my technique)
Since the mini has a conventional stock it will be easier to modify the LOP if you have short arms (the neutered-AR with collapsable stock would be the only eaiser option). Another nice thing is if I ever move out of state it will be really easy to put and "evil" pistol grip stock on it if I want.
The only thing I didn't like was the rear sight which I replaced.
I was able to buy mine for $525 + all the CA taxes & fees so the price is right around the SU16. I don't know too much about ARs; I don't know if you can build a FAB10 for that cheap or not.
I don't know anything about the M96. It looks awkward to shoot w/o the pistol grip. I'm suprised someone doesn't sell a conventional rifle stock adapter for it (though the market probably isn't very big).
I really don't see the FAB10-based ARs useful for anything but target shooting or plinking. They are generally more accurate than the mini but in an actual home defense/shtf situation, having to break the rifle open to reload seems like a very bad feature. I would rather take bolt/pump action .223 or an SKS over the FAB10 for any type of defensive situation since they are designed to load very quicky using a stripper clips or are still allowed to have detachable mags. Turners had a pump-action AK in .223 not too long ago but I don't know much about that particular rifle. The AR based rifle is a bit more complex to strip and clean and may be more sensitve to dirt/debris. Don't get me wrong, if the CA AWB ever goes away (or I can figure out how to legally purchase a "real" AR and keep it out of state) I will definitely be looking into an AR based rifle of my own.
The SU16 is very interesting and I would like to shoot one. I looked at one in the gunshop not too long ago. It was VERY light. If this is your first rifle that will make the recoil seem snappier than the heavier rifles. It will also seem less accurate from an unsupported position since it will be more sensitive to your body's movements. The 10 round magazines that it comes with are plastic/polymer though it supposedly accomodates AR mags. The front sight is also plastic but the su16b which is new will have an AR style metal front sight instead. The bolt is similar to the AR but uses a piston instead of the direct-impingment gas system so it should be more reliable but may still be more sensitive to dirt than the mini. The integral hand-guard/bipod is interesting but I wonder how durable that mechanisim is. I would hate to have my hand guards fall off at the wrong time. The latching mechanism for it was a bit difficut to operate. If I bought the rifle, I probably would not use the bipod feature at all. The other thing about the su16 is that the stock appears to be an integral part of the lower receiver so if the rifle doesn't fit you, I don't know how you would go about modifying it (or fixing it if you screwed it up).
just my opinions,
drc