I have recently complete the Rubank Advanced books 1 and 2 and have been stumped on what I should use as my new book

First of all, I´d tell you to get lessons with a teacher (if you´re not already).

Anyway I think Trevor Wye´s books are very good.

You'll probably like the Soussman studies and Cavaly's Melodious and Progressive studies book one.

Then they get... fun >

Here's a graded list:
http://laurabarron.net/resources/etude.html

*Soussman is oddly graded 8, but a lot of exercises are very much like what you would see in Rubank advanced, certainly a lot of easier stuff than Cavaly's.

I second the recommendation of Trevor Wye's books. They're wonderful.

Trevor Wye's complete book

http://www.amazon.com/Practice-Books-Flute-Omnibus-1-5/dp/0853609365

Taffenael is a good one, just for exercises and for speed and articulations.

Sousmann can be good, if you want to work on arpeggios (earlier on, I haven't done all of it yet).

Hmm... trying to remember which books I did after the first two Rubank books, back in the day. If you like the Rubank books you could get the Advanced Methods 1 + 2 and/or the Voxman Selected Studies for flute (published by Rubank)

Haven't tried the Trevor Wye books so can't comment there.

I really like the Cavally books. I also liked the Wagner Foundation to Flute Playing (published by Carl Fischer). Though technically not a lesson book, I really like "The Flutist Bach (published by Belwin Mills).

Also agree with the recommendation to get a flute teacher if you don't already have one.

Agree with above using Trevor Wye's 1-5 next!! I was using Trevor Wye 1-5 after Rubank advanced 1&2.

My teachers were principal flutists of professional orchestras. They were using these materials on me:

first Rubank beginner..
then Rubank intermediate..
then Rubank advanced 1&2
then Trevor Wye 1-5
then Trevor Wye advanced 6 (except circular breathing - still not 100% able)
then Sir James Galway told me to work on Moyse daily exercises
then my teacher tells me to work on Gaubert exercises now

<Added>

member 'Zevang' above is also a principal flutists of a professional orchestra. :)

Yes Trevor Wye's books are very good and wonderful. Many people said Trevor Wye used only part of the exercises from many many authors, but not complete exercises. But I think they are enough for us students, because to practice ALL the exercises from all the authors is very tedious and laborous. So Trevor Wye did a great work to compile them into 6 books!

Whoa! You met Sir James Galway?!

Sir James has started a scale challenge on his Yahoo Forum. It involves daily practice on the Moyse E.J. book. Exercices Journaliers And the Taffanel and Gaubert Seventeen Daily Exercises for daily studies.
I'd recommend at this level the Melodious and Progressive studies Books 1-4 (#4 has been divided into two books). All of the Andersen studies and the Boehm studies that you can master.
Then there is the Solo Literature:
the Handel Sonatas followed by the Bach Sonatas and anything that you can get from Telemann. ...for starters.
~bilbo
N.E. Ohio