[Eclipse]

I agree that sometimes they try to kill each other. I also agree that they use a lot of resources.
I don't think I have ever seen them fight over what was found but I guess that would be possible if the antivirus expanded what it considered a threat.

While my surfing practices don't expose me to much Malwarebytes is most often what I see blocking on my system.

I run Kaspersky antivirus because I won't run without an antivirus.

A well written virus or rootkit will be invisible and only do what it needs to do quietly in the background so that you don't go looking for it.

I use an all in one kit so it doesn't conflict, like Norton or MSE; it has everything in one so you don't need multiple programs and your PC doesn't slow down.