I personally like
Kaspersky Mobile Security (KMS). Not that there have been any major virus concerns on smart phones, but KMS has anti-theft features that I really like. If someone takes my device, I can send an SMS message to totally lock down the device and then send another to wipe much of my personal data off the device.
They might hard reset and keep the device, but my data and account information won't be compromised.
I don't even use the "auto protect" antivirus, because that just drains resources, but I do scheduled virus scans for kicks. It's quick and I never expect it to find anything
. Really I use KMS for the anti-theft features, I would not use it if it didn't have that. To me the antivirus features are just there in case something ever came up, but not the major concern.