Other. I want the knife to be comfortable to carry so I carry it, and there is more to this than the height it sticks out of my pocket. 1/8" might be acceptable on some designs and not on others. 1" is probably excessive in any case, since I'm going to be sitting and standing.
For the record, my preferred clip is the spoon style standard clip that comes on the delica/PM2 etc. Especially on the FRN designs, the clip hits directly over the "escutcheon" and makes it easier to draw but still holds it secure. Given that this clip already has a dead area where it connects to the scale, I like it positioned as close to the end of the knife as possible.
I've had issues with clips that aren't height related. A few examples:
-The stock clip on the Slysz bowie hit the scales directly over the lockbar cutout, and would snag on your pants when drawing.
-The PPT clip has a relatively sharp end, and even though it doesn't look like it sticks out all that much, it is the only clip I've had trouble with snagging on things as I walk by them or sit down.
Usually, spyderco does a very good job with their clip designs.