Best pens to use for characters to sign fabric with?

[weheartdisney]

I am taking some fabric pieces to have the characters sign this time (only 4 more days!! ). A friend is making a quilt with the pieces.

I bought some fabric pens but they don't seem to write well to me. Should we use a Sharpie...or another type pen? What will stand up to washings?

Thanks!!

 

[aquamindy]

What about fabric markers that heat set?