Along with sharke, I would say usually I don't just use one setting. Some phrases are triplets and need 1/4T or 1/8T or 1/16T. Also, I may quantize a section to 1/16 but then go back and re-quantize parts to 1/8. If I was not playing especially tight, I may have to move some notes manually.
I don't know how much music theory you have, but it does help if you can recognize what should be triplet 8ths, what should be sixteenths, etc. If you don't have music theory, you can still get that by experience.
I would say that if it sounds too mechanical, then try swing. If it just sounds wrong, swing won't help. The only time I use swing is on something like 1/16th hi-hats or tambourines or shakers that are sounding too stiff. In those cases, I set the swing to somewhere between 52 and 56%, with lower usually being better. When you go to 60% or higher, you start to change the rhythm from duple (double) to triple. You don't want it to sound like it is swinging; you just don't want it to sound robotic.
All that said, you can use swing at 66% to change from a straight 8th to a triplet (swing feel) but I don't do that. If I want a triplet rhythm, I record it that way.