I think Ayin's right - It's what works for you. What works for me depends on what I'm going to be doing. If I'm going to be sitting a lot (say for a Burns Supper, theater etc.) I really like my four yard box pleated kilt. It's very comfortable to sit on. If I'm driving or flying I like cotton (Utilikilts) or PV. Not itchy. I love the swing of my 8 yard tank but I wear it to cocktail parties or dancing where I don't have to sit on all those pleats too much.

Nothing else considered, my absolute most comfortable kilt is an old sport kilt that I lounge around the house in.