I love the sentinels' court cards! Those were my first custom court deck and so I have a special place in my heart for those. In addition to that I love the JAQK and Americanas (for their slight alterations).
I agree on the Sentinels - they were a great set of courts (hell, the whole deck was great). And the new releases of them from T11 have much better handling than the first.
Never owned the JAQK deck - I try not to buy decks that support sales of either alcohol or tobacco. But I have seen some images, and they are a cool deck.
I loved the courts on the Americanas. My one beef with that deck was that the 6 and 9 were too close to each other in design and both looked too much like an 8. I've had spectators get confused until I counted out the pips on the card itself.
I'm also a fan of the Shadow Masters courts. They're not phenomenally different, but the whole deck had that "aura-like" coloration to it, and it's one of my first decks I bought outside of a drug store, supermarket or big box retailer. (In other words, from a real deck design house as opposed to straight from the designer/manufacturer, which in most cases is USPC in this country.)