I'm not sure if there's a correct answer. Speaking objectively though (if you can do that), when it comes to image quality and not overdoing it, is there a 'best' option? I hook my PC up to my 4k screen, but I can only get 1920 x 1080. I am okay with that; it's unlikely that I'd be able to play games well at 4k anyways. That being said, playing older games, as an example: Freedom Fighters, the game doesn't natively support AA so I would need to go into the Nvidia control panel to select it, but I don't know which one I should choose. I want to get all the 'jaggies' away, but going past what's needed can make it so not only the performance is worse, but image quality isn't necessarily better (like not being able to see a fence from an angle for example). So I'm trying to find the right balance. Can anyone here point me to the right option? Thanks.

I think this will probably be a situation in which you'll just need to try some different settings and see what is most preferable to you as a balance of image and performance. I found this article that does a quick and decent job of explaining the differences between the types of AA.

Does your monitor have a scaler built in? If so, it might be worth trying to use that to display the image at native 4K, while still rendering in game at 1080p. This will probably be achieved somewhere in the monitor's menu system, with a setting that asks if an image should be displayed at the render resolution or the monitor resolution. With 4K being a 2:1 ratio both horizontally and vertically, the scaler should be able to do a decent job with minimal blurring, but the pixels may be small enough that you can get away from using AA altogether, and further improve performance. Some games have settings such as this, too, in which you can choose the display resolution and rendering scale separately.

@ralphmoustaccio: I use my 55-inch TV, so it's not a PC monitor. Due to the way my PC is, it won't allow for 4k despite my TV being 4k. I've looked into it. The screen fits perfectly fine onto my screen, so no issue there. I don't think it looks bad anyway; pretty happy with it despite it not matching my TV's resolution. Also, I've read through the page you linked to me and then some. I guess I was just wondering if I could get more insight that I haven't read before because there may have been a chance that I wasn't finding what I was looking for with a simple Google search. Even so, thanks for the reply. I was testing it a bit earlier; I wish there was an in-between of 2x and 4x.

@ntm: I definitely hear you when it comes to the frustration of not having more granular control with the settings. Unfortunately, it's so highly dependent on a game-by-game basis that figuring out what the best AA option to use is tough to do. I'd probably start with MSAA at 4x and tweak from there. You mentioned doing it via the control panel for some games that don't natively support AA. If you're doing so, just make sure you're setting that on a game-by-game basis, and not a global setting in the control panel to ensure that it doesn't override settings for games that do have native support.

So by "...it's unlikely that I'd be able to play games well at 4k anyways", what are your specs? 'Cause if we're talking about current or slightly older hardware, you should be able to use Dynamic Super Resolution (DSR) with some older games in order to force 2160p with a TV, if my old GTX 1060 is any indication with me using DSR with Dark Souls II and getting mostly 60 frames in fake 4K.

Also, ENB, ReShade and SweetFX can be options to inject some form of anti-aliasing into the games that support one of those graphics mods or another. SweetFX works with Freedom Fighters.