I agree with most things said by users above. Comodo has its strong points. It's preferable to use Comodo in Cruel Sisters settings. It's very light and mostly problem free that way. Whitelisting blocked apps isn't too hard either. But I had a couple of situations where a couple of apps were crashing for no apparent reason even though they were unblocked.
I had to manually create an allowed application firewall rule for them to work. This was a weird behavior because according to Comodo's logs, the app wasn't being blocked. Anyway, Comodo with Cruel sister's settings is very strong, but it's not a typical AV. With Comodo I even feel comfortable setting UAC turned off like the way she uses it on her PC. I don't recommend it but just saying.
Panda on the other hand is very light and my experience is similar to
@roger_m. Even though AV tests shows that it has a lot of false positives in my experience I never had one as far as I can remember. I had more false positives with MD, BD, Emsi, F-Secure, Avast, Trend etc.
But protection wise, it isn't up to the mark. Like Comdo I can only recommend it to the expert power users who knows how to stay safe, who can differentiate good apps from the bad ones. For them, Panda free is a good choice. It is light, compatible with literally everything and don't even cause issues in any Windows Dev builds. You can also set it to ask mode so that it doesn't automatically quarantine a threat without your permission.
I also last month installed Panda Free on a 2 GB ram Windows 7 system, and it runs flawlessly.
Even I myself am looking for something free and light because Microsoft Defender slows down some things for me. Eg: An online game I play takes 15-20 seconds longer to open with MS Defender than it's with Comodo, Panda and ESET. It should be mentioned that Fast startup is turned off on my PC and MD removes its cache after shutting down or restarting the system every time.