But Avira has better detection rate than avast and is has much much much faster scanning speed than avast!
Really?
Well, if you check some test sites (such as av-comparatives), you'll find out that it says exactly the opposite about the speed, and even the detection is questionable.
No. I've tried the latest version of Avira Personal (about a month ago) and test it against my personal malware collection and the detection rate is on par with Avast! Free.
Avira scanning speed with it's standard settings is quite fast, however for better security setup you need to tweak the setting in Avira which resulting in a slower scanning speed.
Avast with standard settings is definitely faster than Avira. Tweaking the scan option for a better security still resulting in faster scan compared to Avira.
One interesting thing to add here is the latest Avast using my computer resource lesser than Avira either on standby/idle or while doing a full scan.
Personally, I regard Avira as an alternative to Avast. I use Avira about two month ago for a month because Avast 5.1.889, 6.0.1000, and all other version which come afterwards keep freezing my Windows randomly but often.
My overall experience with Avira is quite pleasing (except the old horrible UI). Still, since Avast 6.0.1125 seems to fix that random freezing, I'd wholeheartedly prefer Avast (resource friendly) over Avira.