Is this for AV version or for IS versions?
In my experience, Avira has been the least resource consumption solution, out of the 3 listed.
Kaspersky has a busier CPU when the scans run in the background, however BitDefender somehow makes the system slightly slower compared to Kaspersky. Bare in mind that on an High End system, the resource usage is not that noticeable.
If your system is not High End and you are focusing on resources, then stick to Avira.
If you want more features and protections, then thats a different story, but original post should be edited to reflect such request.