Really? I know it's a thin profile, but that's faulked. Maybe it's flexing from the receiver/trunnion/however it's attached... Anyways, watch the Nutnfancy video on the SU-16. He sings its praises as though it's a steal. I can't get over some of the pictures I've seen of users cracking the back of their receivers apart from firing.
Nutnfancy seems to be very good friends with the Kel-tec guy so his reviews are always very positive. I would not rely solely on his review.
I've owned the Sub-2000, RFB, and KSG and all worked fine, the 2000 was very cheap feeling but it did what it was supposed to do when you pulled the trigger, was surprisingly accurate, and once it was broken in it was very reliable. My experience with the RFB and KSG were both very positive. Both were gen 2 models and functioned perfectly from day one.
I've shot two SU-16's and both functioned perfectly but the standard model had horrible accuracy, it looked like we were using a shotgun after a couple boxes of ammo. We tried a few different types of ammo as well but nothing tightened up the groups. The other one was the FX or tactical model or whatever it is that looks like an AR and it was a much better rifle than the standard model, it felt much more solid and the accuracy was pretty good.
Back to the original question,
For $1000 there really isn't anything of quality.
-The SU-16 series are in your budget but you will end up selling it for a loss in order to upgrade once you realize how much more rifle you get for $500 more. If you do go this route I would only consider the tactical model as it was definitely a better built rifle than the standard folding model. The biggest pain in the arse with these is stripping for cleaning, they are not very user friendly in that regard.
-The T-97 is a disposable rifle with no warranty or parts support. They suffer from the typical QC issues everything that comes from China has, if you get a good one you will be happy but you're just as likely to get one built out of spec and you'll be frustrated till the day you sell it.
-The Mini-14 isn't really a "black" rifle and in order to dress it up to be more tacticool you'll end up spending as much as a used Tavor or XCR-L would have cost you.
-The XCR-L had some growing pains in the earlier models and has never been know for it's accuracy but at least the newer ones seem to have sorted out the issues and are pretty reliable with excellent support from Wolverine Supplies. With used ones on the EE for under $2000 these days they are an excellent choice as long as you don't plan to sit on a firing line trying to make small groups on paper.
-The Tavor is also an excellent rifle if you are ok with a bullpup, accuracy is not it's strong point but for CQB, 3-gun, etc it's hard to beat once you get used to the ergo's and controls. These can also be found for under $2000 these days making them one of the best buys out there now.
-The HK SL8- series is also a great rifle, I've owned three of them and all were set up differently, two of them were able to shoot 1 moa with quality factory ammo or handloads, I sold the third one before I had a chance to do any load testing but I'm sure it would be no different than the others, the rifle is heavy but is very reliable and probably the most accurate factory offering available.
-A used AR-180B-2 would be a good rifle if you can find one for under $1600 in original condition (I hate it when people try to turn them into an AR). They are reliable and provide decent accuracy but parts are hard to come by.
The CZ and VZ series are decent rifles but they are for the most part a fancy SKS and I'm a firm believer that if you want something to be reliable you don't take a rifle designed to run 7.62x39 and convert it to 223 or the other way around. They are designed to feed a certain shape of ammo from a certain type of magazine and when you mess with that stuff without actually re-engineering the rifle you will usually end up with something that doesn't function as well as the original.
The other options worth considering are going to run you $2500+ even on the used market so unless you're going to up the budget I'll leave it at that.
I would suggest skipping all the pistol caliber carbines unless you never plan to shoot past 200 yards and you really just want something that looks cool and makes more noise than a 22. I've owned the HK USC, a couple Kriss Vector's and the Sub-2000 and all of them get boring really fast.
I would buy an American made AR to start with as long as you have good access to a certified range and you're ok with using it at the range only. It will put one of the best rifles in your hands within your budget and allow you to shoot while you save up some more money. When you're ready you can sell it and move to something non restricted, this will also give you more time to research and hopefully get a chance to shoot some other rifles to get a feeling for what you really want. Even though the Tavor/X95 is an excellent rifle the bullpup design isn't for everyone so dropping $2000 just to try one out may not be the best plan. I had a chance to shoot four of them before I bought one for myself, I never got the big smile feeling when shooting the four that belonged to someone else so figured that since everyone was still raving about it I would try one for myself. After three months I sold it, nice rifle, built well, reliable, accurate enough for play time but just doesn't do it for me.
Remember to budget for ammo and some sort of sights so basically put $1000 aside just for that. Semi auto 223 rifles are very hungry and can suck back a lot of ammo in an afternoon, you can easily drop $200+ an afternoon just having fun ringing gongs. Even cheap 223 is around $0.50 per shot so keep this in mind if you don't have a decent amount of disposable income.
Good luck.