online forums are a nerds paradise. Most forums attract a higher number of nerds than in other environments. Nerds as a group tend to lean towards fantasy and sci fi. The result is that is the most common book talked about.
So starting a thread in other subject matter will get a lot small number of people joining in.
I read a mixture of sci fi and horror. I found goodreads was great for horror book talks.
If you tell people here what subject interests you they may be able to point you somewhere that will give you back the feed back you want
applesauce