The only real options for a great seat are VX, CO on the 752 only and DL on their BizE 752 only. DL and CO can swap aircraft on the route so that is a risk you take. VX only has the one config for F seats so that is the most likely to actually get you flying what you book.
The DL plane only has two classes of service, Y and F (on the JFK-LAS route) and the F is the BizE seat on those planes. If there is an aircraft swap you get a typical domestic F seat.