You can update AVG as often as you like - I suppose tho that you mean that sometimes when you click "update" there is nothing to update; I can't see why you think this makes it less good than another antivirus - it all depends what other companies are including in their antivirus updates. My AVG is set to update daily and somedays there isn't anything, but it works and I'm happy with it.
I've used AVG for over a year. I use the free version. I haven't had any virus problems in that time tho friends with other antiviruses have had, so I feel it is working. I switched from Mcafee which I found incomprehensible & wouldn't do what I wanted when I wanted. Norton was just as bad AND you have to pay for those.