well i have used both Avira and Avast.. and have to say that avira is much better than avast at detecting trojans.. and gives a better real time protection..
for avira :
pro's: excellent scanner.. very good at detecting trojans..anti phishing, fast scanner,good realtime protection, can schedule scans..antirootkit etc
cons: delays startup..,updates slow,ads pop up while updating.. (behaves like a adware while updating.. thts kinda annoying), AND NO ANTISPYWARE...also tends to hang up when installed on heavyly infected comps..guess tht certain viruses disable the software..\
for Avast:
pros: good detection rates, has an inbuilt antispyware as well as antirootkit..realtime protection is good..(avira's better)..also comes with a basic firewall,best part is it has a scan on reboot option.. so anyvirus tht tend to hide on reboot are detected..has a strong self protection..(it cannot be disabled by viruses,While AVIRA CAN BE) P2P shield nd IM shield
Cons: not good at detecting trojans,anti spyware isn all that gr8,(Ad-Aware's better) scanning takes really long time.. specially if there are video and music files on your comp..which is annoying..
in the end despite many advatages of avast.. i would stick on to avira.. as it as better detection rates than avast..and for comps in which avira hangsup would suggest u all to install avast.. update.. run a scan on reboot than install avira again..my recomandation for a malware free comp in avira,ad-aware, and comodo firewall..