Hi, I assume you mean Avast not advast.
I would personally never go for AVG antivirus, due to its awful virus recognition record, it does however have a link advisor compatible with FF and IE.
I have never used Avast and can't comment to much on it but from the feedback from other members of this forum I think it's ok, not sure if it has a link advisor.
I offer you a third option which is always the option I would go for if using free antivirus; Microsoft Security Essentials.
MSE has one of the smallest footprints and highest virus protection rates of all the free antivirus software out there. It does not come with a link advisor (I think) but I think if you use FF you can download AVG link checker without having AVG Free installed.