I like Blues and Purples.
But of course there is always the flavour of the month.
In the cheddar you can't go wrong with pink either.
What it comes down to is use a pattern that you have confidence in.
Saying that though, I also like orange, yellow, red, chartreuse.
But nine times out of ten if you ask what is on my line it will be purple and/or blue.
Stick with it and they will come.