My favorite section changes over time.
At the beginning it was discussion about the brand-new, state-of-the-art, newfangled technology called e-ink. Only one reader in the world featured that - the Sony Librié.
Later when I purchased Sony Reader PRS-500, it was forum about hacking of PRS-500 and, of course, libprs500 - the Calibre predecessor.
A few years later I have purchased PocketBook reader and we had great time on PocketBook forum.
Nowadays, I usually go to the main page at
www.mobileread.com and check "the latest activity" several times a day. I also check all my subscribed threads.