Never used ESET, so I can only vouch for Avast, and I find that it's boot time scan is incredibly useful.
But I'd definatly call this an Apples Vs Orange debate as one is a free AV and one is a paid security suite. Most people are usually attracted to the FREE price sticker anyways.
I don't actually use an Antivirus, it's just a personal preference. I like to live on the edge .