You are most welcome. I'll assure you also by saying I promise your battery will not take a beating lol. Most of these apps have become more efficient now, less resource and battery intensive.
I prefer avast. It scans apps and files on the internal and external memories, scans apps on install, has an ip table firewall, privacy options, stolen phone options and more. It has a small memory foot print (about 10mb). No noticeable battery drain.
I recommend avast due to functionality that it has that others don't. Some swear by avg, lookout,nq and others. You could try a few and figure out what you like best.