I prefer a soft catch anyday. I would rather fall an extra x - feet and get a soft catch (assuming the fall is clean), opposed to slamming my ankles against the wall.
If your worried about giving someone a hard catch, don't. I wouldn't want to feel responsible (assuming they asked fot it, it would be their fault) for someone spraining an ankle, or what not.
I like just enough slack to allow for a quick clip or long movment without carring my belayer up the rock, but don't like excessive free fall. All this is assuming we are talking about vertical or overhung routes. On slab I prefer as little slack as possible, and a hard catch is more than fine.
If you fall i will catch you, i'll be waiting...time after time (classic 80s anyone?). As long as I don't feel the threat of decking, i supppose soft is sufficiently sweet sans slabby pitches. It is pretty hard to deck when all you do is TR, there has to be a good amount of slack and rope stretch though i've managed to do it, ask my roomies, i fall with the worst of them (technically unproficient). I guess the next question should be briefs, boxers , boxer-briefs, or commando?
"well Sco doesn't have my peripheral vision" - mason allen reminding us all that our peripheral vision often overlooks creepy crawlers and flying things.
It has to be sooooooft. Kirker is usually my belayer and he gives a pretty soft catch. He has often said he's going for belayer of the year. My wife gives me a soft catch too, but thats from the weight difference.
From a guy who likes falling and hates slab I'd say soft or nothing.