Although dated, this thread still gives you good advice/pointers:

http://www.flyertalk.com/forum/miles...-programs.html

Not knowing what and how many miles you have, the general rule of thumb is to do your best to accumulate miles in one FFP and fly the same alliance so miles can be credited to the same account. Keep that in mind when you plan for your future travels.

Having 100K miles in say AA is much useful than having 20K each in 5 different FFPs, especially when you now have a goal to fly in C cabin. If you do fly as much as you stated, chances are you may have achieved (top tier) elite status if you had chosen to stay loyal to one FFP. Not to mention one benefit of having elite status is the instrument to upgrade and/or comp to business class.