From a strictly monetary point of view, I'll disagree and say the DD should be last to use. The first razor you use is honestly the one that you can choose in answer to this question:
Which one would you be most willing to throw onto the floor and pound with a hammer?
The reality is that beginner's make mistakes. They drop razors, they bang them against sinks, they roll the edges when stropping, and who knows what else. All of those razors should be good shavers so that's not really an issue. Pick the one that you personally would be willing to sacrifice. Then, be very very careful with it!
I admire your patience in posting this question!