It varies according to the pattern, but my default is the thumb method, as that is the cast-on I was taught when I learnt to knot at 7. I use the cable method if I want a stretchier edge, and have a book of cast-ons and cast-offs if I need a fancier one. I am very definitely a 'thrower' though, so some of the ones that involve 'picking' the yarn just don't work for me.
Anyone see the first episode of The Party?
Yes I know it is early but....
