I also use Avast, and have also tried AVG from Amazon Underground for free (a potential security risk in itself), as well as 360 Security.
I found 360 Security tried to do too much: things you don't want it to keep doing like optimising memory usage for large apps. AVG seems fine except for the fact I got it from Amazon Underground, and I can't help feeling Amazon themselves may be doing something unwanted. For now, AVG is on my tablet, along with Amazon Underground which is required for the full version of AVG they provide to work for free.
Avast works fine, but like 360, they're now bugging people with unwanted messages which require a purchase from them, which with Avast it is about WiFi connections, in order to sell their VPN product.
I know they need to make money somehow, but Avast as it stands is "tolerable". If they push it any further, I'll be looking elsewhere for security software on my phone.