IMR 4350. I have never shot any other powder from my 06, never needed to.
I was in the preliminary stages of load development when I ran across Dan Newberry's website.
http://home.earthlink.net/~dannewber...addevelopment/
You may have seen this before, but if not, he uses an interesting technique for developing his loads. He refers to it as Optimal Charge Weight Load Development. Some agree with him and some don't. I thought it was a good read. He has a great load for IMR 4350 and 165gr bullets. I followed his technique, with my 06, and found his recommended load to best from my gun also. I've not tried any other calibers he has listed.
Hope this helps,
Toby