Which AAC setting should I use?

[EyeAm]

Greetings all,
I am converting my FLAC files to AAC files to play on iTunes (and I want new CD rips to convert to FLAC and AAC). Which AAC do I use? Should I use the one that clearly states for itunes (m4a QAAC iTunes) or is the m4a FDK AAC better? Does it matter?
Is there a limit to quality of the AAC file for iTunes? Should I stick with tVBR/125 kbps or can I go with CBR 320 kbps or highest possible?
Or, is there a different AAC setting you would suggest?

Thank you for the guidance and enlightenment.

[Spoon]

Re: Which AAC setting should I use?

Higher quality gives larger files, if you go to 320kbps cbr then all encoders would generate very similar sounding files.