I would nominate the new class 08 as one of the best models Hornby have made. It has the best running ability of any locomotive I've seen from Hornby or other manufacturers, crawling at a rate measured in millimetres per minute. The detailing is exceptional as well; it has details such as pipes running below the footplate where they can only be seen from a narrow angle and individual throttle levers in the cab, again difficult to see without close examination.
Are Hornby using the same drive mechanism in more of their models now? I think it's similar to the J50 tank, but perhaps also the GW tanks.