I like reading on relationship questions. But I don't think people always like me reading on them. LOL It's such a thing of fantasy/fun for people to read on and get readings on, and I don't feed into that fantasy/fun.
I think spiritual topics are tricky, but they don't come up as often. Where someone assumes something that may not be true like "Why am I cursed?", or something like that which I don't believe in, because then I actually have to try harder to put myself in their shoes to understand where they are coming from and interpret a reading without sounding like an asshole calling them crazy. Plus, I just value other people's cores and hope to preserve their lives the way they are, to learn whatever it is they need to learn on their personal path.
Next would be financial matters- never got a lot of practice with those, and it's a weak area in my own life. Health is about the same- not a lot of practice with those.
Following financial/health matters it would be work issues... but even the work readings I do seem to come up more focused on the interpersonal relationships. So relationship questions are really my "thing" I think.
So.. spiritual topics are probably my least favorite. They are the most personal and unique paths for people, and it's hard for me to get my feelers in someone's energy on those.