The USAF is doing a Light Attack and Armed Recon comp. To be honest both aircraft in this are appealing but to be honest, if I had my druthers the USAF would buy American (not assembled in the US...US built).
My opinion and the USAF will do what it wants. Info on both planes follows.
AT-6
AT-29
f.r3_at6_brochure_flipbook
Note: Embraer does not have a brochure for the AT-29