I understand that ccTLD domains could not compete with .com and .net domains but how about with other TLD domains. E.g For something like accepted.at and accepted.biz which is more valuable in your point of view. I like to know your opinion. "Accepted at" is commonly used worldwide and it is also domain hack. So do you think TLD domains including biz, info domains are always worth more than .at domains?
Not necessarily. When you say 'worth more', it depends to who, a reseller or an end user. IMO, it depends on what the end user intends to do with the domain. If their business is targeting the Austrian market, then the .at domain extention probably has stronger branding/mindshare than .biz or .info. This is clearly illustrated by the strength of the .co.uk and .com.au extentions, amongst others.
Agree with you, besides Austrian domains cost you more money and unless you have a great marketing plan that justify the name, there a little chances to develop a great site. Good exceptions could be look.at, go.at, etc.