It depends for me. Since I'm 6'5" and most of my height is in my torso, it's hard to find ties that are long enough ("tall" ties are extremely limited in selection). If I can find a long enough tie, I do like the look and class of the Windsor knot, especially with a collar bar underneath.
However, given that lots of my ties aren't long enough, I do tie the Shelby and half-Windsor too. Most of the time, I end up needing a tie pin, since the tail is often too short to meet the tab.
[rant]When the hell are dress shirt manufacturers going to start making something other than white, navy, and black variations in tall sizes? 17.5X37 tall shouldn't be that hard to find![/rant]