I always wonder that myself when people ask what male/female they should get next. To me the answer is simple: what do you want that you can afford to make?
My first breeding goal will be axanthic fireflies. Then I'm going to move on to making lots of other axanthic combos. My goal on the side will be jigsaws since I already have a pinstripe male and I love their patterns. I'm the same way as you, I've gotta have a goal. I don't want to just toss snakes at each other with no set direction to work towards.