Well I'm a fan of Kef speakers and I would argue that they are on par (i.e. same class) with offerings from PSB, NHT, Canton, and etc. They have British roots and have a tendency to be more laid back in comparison to Klipsch, MB Quart, and other speaker brands that I have auditioned. For those that don't know, Celestion and Kef are owned by the same holdings company. Depending upon your budget, room size, key features you're looking for (i.e. DTS-MA and etc)... I would suggest looking into Marantz or Denon for your AV-receiver duty. If you have coin to spare... Separates are always nice... From Rotel, Adcom, NAD, and so forth... As for the subwoofer, I would do like the guys here suggested... Go with SVS, HSU, or Velodyne... But please note I've only had experience with Velodyne, M&K, JL Audio, Polk, Bic America, Athena, and a few others in regards to subs.
ps: Kef speakers + Rotel Amps = very good experience (for me) Just my opinion though