Probably the best option is to look at a balance of performance, malware, and real-time protection. For example, consider the results here:
www.av-comparatives.org
The top free AVs would be Avast, AVG, Bitdefender, and Kaspersky.
From there, adjust to see which is lightest in your system, i.e., given both benchmark testing and what you experience as you load the browser and view many pages, browse folders with a few and lots of files, and load, view, unarchive, etc., big and small files.
And then add to that how many upgrade popup notifications show up, and whether or not it will cause problems for novice users like friend and relatives to whom you recommended the AV, and if you'll have enough free time to answer their questions or check their machines to see if something went wrong. Add to this friends and relatives who are intermediate users and notice and complain of slowdowns, including those that edit videos or play resource-intentive games.
Given that, from the four I'd recommend the ff., but with the ff. issues:
Avast - turn on gaming/silent and "do not disturb mode"; the problem is that the only way that users will know that something is being blocked is that a blue dot will show up in the system tray; I don't know what will happen if notifications are turned on, but I remember annoying upgrade notifications show up; (one thread says that this is no longer a problem with the new version of the AV);
AVG - I can't remember, but this felt slightly heavier than Avast, and I had to do an in-place repair upgrade of the OS to remove parts of it that were still in the system even after a complete, clean uninstall using the company uninstall tool;
Bitdefender - essentially set-and-forget, but also feels like it's the heaviest among the four; also, it always complains when I turn off HTTPs scanning; and
Kasperksy - an annoying popup notification for upgrading still shows up once a month (after turning off any notification settings plus those in the web portal); it also feels like the lightest in my system (a new PC running Win 11 Pro).
Lastly, about the built-in AV, it was the heaviest in terms of benchmarking, especially when core isolation is turned on. I didn't feel it when I loaded the browser (Firefox) but did when I did file operations.