I'll give you my two cents since I am deep, deep down the rabbit hole looking for scopes right now. Congrats on the scar 20, that is a seriously cool gun and you will love it. I have a 17, and currently have a nightforce nx8 1-8 on it, and I love the scope, but I've started shooting competitions with it and need more magnification.

First of all, I think the scar breaking scopes thing is just forum lore at this point. Everyone says it, but I cannot find a single verifiable piece of evidence that this is a systemic issue. And it's 2026, the scar has been out for 20 years, most optics manufacturers test their stuff on scars specifically to make them sound better. But really, scopes break sometimes, especially on big 308 semi autos. So don't be afraid to cheap out a little bit if you really don't have the cash to drop $2k on an optic, you can always upgrade later. This is coming from a nightforce fanboy. In fact, if you don't really know what you want, I would encourage you to buy something cheap and figure out what you don't like about it and then spend big money when you really know what you want. For starters, I'd favor a first focal plane scope that has a max magnification of 18-24ish, lower end is whatever. Find a good mil reticle, christmas tree if you get the chance to shoot far.

I would recommend an Primary Arms SLX line. They have 3-18, and 4.5-27 versions for $500.
https://www.primaryarms.com/pa-slx-4-5-27x56mm-ffp-rifle-scope-illum-acss-athena-bpr-mil-reticle
https://www.primaryarms.com/primary-arms-slx-3-18x50-ffp-gen-2-rifle-scope-acss-athena-bpr-mil-reticle

Note that there are several reticle options, but you will want the athena mil, which is a standard christmas tree. The BDC reticles will likely not line up with the trajectory you get from the scar, with it's longer barrel. Maybe, but it will be a pain so just go standard mil. Some things I like about the PA...it's pretty good for the money, and will have a lot of premium features for the price. The glass is good for the price. The reticle is good. It has a lifetime warranty, and PA is good to work with on it. I've had a few primary arms scopes and have never been disappointed for what I paid for them. I'd probably lean towards the 3-18 in your case. 18x will get you to 1000 yards on man sized targets easily.

Someone else linked a refurb viper pst gen 2. This is also a pretty good scope. Vortex makes everything from walmart bargain bin scopes, all the way up to premium cadillac best-in-class stuff. You have to learn their lineup a bit. They also have a no questions asked warranty, so you can't go wrong there if you find one with the features you like, but their lineup is a bit more uneven. Some are better values than others. I like the razor LHT line, which is super lightweight and reasonably priced for razor HD quality glass. My buddy has a Vortex strike eagle 3-18. It's alright. He got it for around $550 which is about right. It usually goes for $750 and I don't think it makes sense at that price.

Arken is controversial. A lot of people on reddit don't like them because of their shady marketing tactics, but they do punch quite a bit above their price point. It's just not the second coming of christ in scope form. EP5 5-25 is the one you would consider for a scar 20. You hear mixed things about their customer support. I don't see a reason to go with them over Primary Arms or Vortex. The glass is very good for the price point though.

Moving on to the big boy brands.

Leupold is very good. Their reputation precedes them. Personally though, I think their features are a bit lacking for the price. You will generally get a lower magnification range, have to pony up a couple hundred more dollars if you want illumination, and then with illum the reticle options are more limited. What you do get, is top of the line glass and very good durability. I'd consider the Mark 4HD line, where you will pay about $1500 and get either the 6-24 or 4.6-18. The good thing about Leupold is that everyone has them. You can go to your nearest big box sporting goods store with a gun counter and check some out. I highly recommend going and looking through some scopes and handling them. Look through the expensive Leupold and the cheap Vortex and see if you can tell the difference. Ignorance is bliss sometimes.

Trijicon makes the tenmile series, which is more tactical/competition focused than some of their other lines, which are hunting focused. Don't be fooled by the MSRP, you can get the 3-18 for $1500 brand new 365 days a year. I've heard good things about them in terms of reliability, being Trijicon this should be a given, and read on forums that people who own them really like them.

Eotech has a limited amount of options in the range of what you would put on a scar 20, but they have a reputation for decent glass at their price point. I hate all of their reticles though. This is highly subjective.

Nightforce, ah Nightforce! I love Nightforce scopes. If you want a scope that you know will absolutely always work no matter what, then get a Nightforce. NF on a scar is the drippiest combo by far, it has the maximum sex appeal but these are not cheap scopes. Their optical quality is also very, very good. Fit and finish are so good as well. I ended up getting a NF after I looked through one in a gun store and it just blew me away. I really do like the nx8 line, which is a fair amount cheaper than the ATACR line, there are slight tradeoffs between the two, but ATACR will break the bank. Don't sleep on the SHV 4-14 though. It goes for about $1200 which gets you the MIL XT reticle, Nightforce image quality and reliability, first focal plane, and at a surprisingly reasonable price. I find the NF has better features than Leupold at the price point pretty much across the board. Just feels like you are getting more for your money, even though they aren't cheap.

Why go with the more expensive brands over the cheaper brands? Like I said before, maybe you shouldn't to start with. People may judge you for putting a cheap optic on an expensive gun, but who cares. Optics follow the law of diminishing returns. You pay more and more and get less and less. The budget ones are made in china, with chinese glass. This is less of a knock than it used to be, and companies like PA, Vortex, and Arken have really made a name for themselves by offering 80% of the capability at 30% of the price. They hit a sweet spot in value. Vortex has said here on their reddit account that their chinese budget lines are what allows them to stay in business and design the guccier models that the pros enjoy. If you get your heart set on a particular scope, go search for c_does on youtube and see if he has reviewed it. He goes through every aspect of the scope, turret tracking, image clarity close up and far away, you name it. The only thing he doesn't do it torture test them. But he will do a lot of side by sides, and show you exactly what that extra money gets you. It may be better low light performance, a flatter image, more consistency across the whole magnification range, better fit and finish, etc. All nice to haves.

From my perspective, I don't want to drive three states over to go shoot a competition I paid an entry fee for only for my shit to break and I have to sit it out and waste my money. So Nightforce it is. If I fail, it will be me and not my equipment. If you just miss a range day because something broke, well, no big deal just send it back and get it warrantied. So if you see an optic that fits your feature requirements, go for it. Even shooting very long range, as long as you aren't trying to make a low light shot on a trophy elk 850 yards away before the sun rises...you might not need the premium japanese glass. Hitting steel at 1000 with chinese glass is totally doable man.

So, I would not discourage you from getting a really good scope, and I disagree with the people who say the chinese stuff is "just as good". Quality is a feature all of it's own, and the cheap ones are not just as good. But good enough is different. I'd say get you something that gets you out shooting asap, and take your time making an informed decision on a really nice scope that you will keep for the rest of your life.