It took me a lot of testing apps, but I find Connect or Boost best for lurking, as I find them the prettiest UI.
Summit I love for posting due to having the best feature set, and the UI is there with the best of them as far as customizations, but I just can’t get it to look quite as polished as Connect or Boost.
Sync I kept around for a while to, but it didn’t have the feel I was used to with Liftoff.