My experiences:
360ts (avira and bd off):
Low ram usage 45mb, less than my browser tabs or windows proces (WWAhost.exe 118mb, explorer 50mb)
BB
fast scan.
Speedup, on manual give me great tool to control autoruns...
Avast:
Black screen bug (w8)
Ransomware on family computer
New version, reboot to update, (after reboot) new version, reboot to update, (after reboot) new version, reboot to update, (after reboot) new version, reboot to update...
I'm still on 360 waiting next comodo release (memory leak on my W8.1)