I found myself in a similar situation and what I did was I read the profession section of the forums, checked out different classes/builds. Read what people said about each class, both pros and cons. Leveled a char until I had a feel for that class, jumped into the heart of mists and tested out certain builds in pvp. That gave me an idea of what char I wanted as my main.
You have a thief, warrior and mesmer but which of them do you find the most fun and which suits your play style? It should come down to what you enjoy the most. You mentioned that you wanted to be able to farm the cof warrior/mes groups, you can always make a char solely for farming too.
As for your asuran mesmer, you seem to have your doubts about it and were thinking about rerolling as a human. Personally, I wouldn’t want to spend all of my laurels/gold on a char I wasn’t sure about. Maybe you should keep that char for farming/pvp until you decide. Might even be worth making a human mes [not deleting your current one] and play around with it at low lvls and see if you think its really what you want and if you think it’s worth it to re-roll.
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