I don't think you should be thinking in terms of Warden or Quartz. Mostly because I don't think you should buy Warden. I think Warden and everything beyond is a statement of being earned. You will also need Warden for the later lines of armour.
I might be an oddity in that line of thinking.
Looking at the two, Quartz is better than Warden, but we don't know about Dragon. I think you should quest for Warden, and do what you need to do for other armour in between.
Alpha393 wrote:I tried that but no one wanted to kill the bosses I needed to kill
How are you going about this? You might have success shouting "Looking for Shadow Armour team."
You may not get an immediate answer, but trying over few days might find the team you desire. By doing this (rather than shouting "Who wants to kill Entron?" you imply that you will stick with the team until all bosses that are needed by group members are killed. It is more inviting.
You might also catch the odd empathetic high level willing to help.