Tip up for me atleast for right now. Mainly so I can use the wave. Reason i may go back to TD carry is because i get a better purchase on it and i can spydie drop it which always looks pretty nifty to me :D
I also let the design of the specific knife dictate position, but I rarely use a clip. One of the first things I generally do with my Spydies is ditch the clip, slap on a minimalist lanyard, and drop it in my pocket - right front for primary EDC - flatter designs may get back pocket duty. I generally have one knife in each of those two pockets ...
"In theory, there is no difference between theory and practice ... In practice, there is."
I prefer tip up because the knife is more comfortable in hand when opened. With tip down the clip interferes with the critical portion of my grip, whereas with tip up the clip is in my palm where I hardly know it is there. I have found this to be true with all my clip-equipped knives, so I standardized on tip-up carry when clipped.
Of course, tip-up is the only way to go for wave opening, but my main EDC's are not waved.